Tonight is the NBA draft lottery, which is one way to build a team.

The other way is free agency, which starts in just over a month.

Many teams positioned themselves for this summer, expecting Dwight Howard, Chris Paul and Deron Williams all to opt out and become free agents. But Howard and Paul opted in, and now there is money to spend on a significantly weaker but nevertheless strong class.

A handful of teams could be very active this summer. Among playoff teams, the Indiana Pacers appear to have the most flexibility, although in Roy Hibbert and George Hill they have a pair of restricted free agents they will be interested in keeping.

Meanwhile, teams such as the Boston Celtics, Dallas Mavericks, Los Angeles Clippers, New Jersey Nets, Phoenix Suns and Portland Trail Blazers have several rotation players who could be on the move, and will have to work quickly to avoid picking up scraps.

Here’s a rundown on the top 20 unrestricted free agents, with another 10 meriting honorable mention listed below (Tomorrow, we will rank the restricted free agents):

1. DERON WILLIAMS: The crown jewel of this summer’s free agency class has an opt-out which he will certainly exercise after telling the Nets earlier this season that he would not sign a contract extension. The top-five point guard remains the best lure for Dwight Howard because he is a superstar sidekick who will give him the ball but won’t get in the way of Howard’s off-court dreams. Still just 27, Williams holds all the cards and could dramatically impact the future of no less than three teams – Brooklyn, Dallas and Orlando. DESTINATION: There is an outside chance he could return home to Dallas – with or without Howard – but Brooklyn has a much better shot.

2. GORAN DRAGIC: The NBA has become a point guard league, and the 26-year-old lefthander from Slovenia is among the best available. In 28 games as a starter, he averaged 18.0 points, 8.4 assists and 1.8 steals while shooting 49 percent from the field and 38 percent from the arc. He even kept his starting spot after Kyle Lowry – whom many were touting as an All-Star – returned from his bacterial infection. DESTINATION: The Rockets want to re-sign him but may get pulled into a bidding war with Portland, which is done with Raymond Felton.

3. KEVIN GARNETT: Who wants a 36-year-old jump-shooting 7-footer with 50,000 minutes (including playoffs) on his odometer? Who doesn’t? In a league devoid of quality centers, Garnett showed this season that he can play the pivot just below an elite level as he enters the twilight of his career. He is still an excellent defender with a thirst for competition and championships. He will need a caddie going forward, however. DESTINATION: It’s hard to imagine him moving on at this stage, and if the Celtics give him $15 million for two seasons, it should get the job done. But if Boston low-balls him, there will be plenty of interest.

4. STEVE NASH: Yes, he’s 38 years old – and he still nearly singlehandedly lifted the Suns into the postseason. He led the NBA in assists for most of the season, shot 53 percent from the field and still makes everyone around him better. If you’re wondering about durability, Nash hasn’t missed more than seven games in a season in over a decade, although Phoenix’s training staff has had a lot to do with that. DESTINATION: Nash spends summers in New York, and the Knicks are a lot closer to contending than the Suns, who still hold the rights to restricted free agent Aaron Brooks.

5. ERSAN ILYASOVA: Just 25, the native of Turkey is not your typical allergic-to-paint European big man. He is coming off his best season (13.0 ppg, 8.8 rpg, .492 shooting) and had some monster games on the backboards. After averaging under 28 minutes per game, he is ready to become a 36-minute player. DESTINATION: He could command eight figures annually on the open market, but the Bucks have the future cap flexibility to keep him. And with Andrew Bogut gone, they have to keep him.

6. KRIS HUMPHRIES: The only double-double guy on this list, and he now has done it two straight seasons after career highs of 13.8 points and 11.0 rebounds. Made $8 million this season – not counting the residuals from his brief stint as Mr. Kim Kardashian – and should be able to get more annually on the open market. An ideal fit for many teams because his points come without having plays run for him. DESTINATION: Best bet is to the Magic, in a sign-and-trade package for Howard.

7. GERALD WALLACE: Has a player option and has flip-flopped on it, initially leaning toward keeping his $9.5 million, then saying in late April that he may opt out. Hard to imagine him getting that much this summer, but may want the security of years instead. “Crash” is just 29 but has a lot of bumps and bruises on him, and his scoring and rebounding have dropped considerably since his 2010 All-Star campaign. A gamer who will attract solid interest. DESTINATION: Also could wind up in Orlando, although he would be an ideal fit in Los Angeles if the Lakers could move Metta World Peace.

8. RAY ALLEN: There may be some alarm due to the 36-year-old’s postseason shooting slump, but we believe that the bone spurs in his ankle are the reason. His late-season transition to a reserve role is intriguing, because that is probably his future status, where his shaky defense will be less exposed against fellow subs. Still strokes it better than anyone. DESTINATION: If Allen is willing to take a pay cut from his current salary of $10 million, he will be in high demand. At the mid-level, the can’t shoot-straight Grizzlies could plug him in for O.J. Mayo.

9. JASON TERRY: Now 34, he needs 2,513 points to surpass Eddie Johnson for the highest-scoring non-All-Star. Still averaging 15 points, still sumpremely confident, still a threat from the arc, still a factor in the fourth quarter. But his days of eight figures per season are over. DESTINATION: It’s hard to imagine him not with the Mavericks – only Dirk Nowitzki has been there longer – but Dallas will bring him back only if it strikes out on Williams and/or Howard. The Clippers could say good-bye to their multiple free agent guards and bring in the more consistent Terry, who would thrive alongside Chris Paul.

10. CHRIS KAMAN: In a disjointed season that included a trade to a bad team, another injury and a brief benching while the Hornets explored a trade, Kaman still averaged 13.1 points and 7.8 rebounds, a slight uptick from his last season with the Clippers. Although he is 30 and has had significant injury issues over the last five years, he is a quality center, which are in short supply. DESTINATION: Depending on where the Hornets end up in the draft, he could come back at about half his $14 million this season. Philadelphia, Miami, Portland, Orlando and Milwaukee would be good fits, but only the Blazers and Bucks have the cap room.

11. LOU WILLIAMS: Only 25, he as an early termination option on his current mid-level deal and reportedly plans to exercise it and strike while the iron is hot after leading the 76ers in scoring with a career-high 14.9 ppg. An ideal third guard because of his handle and ability to get to the line, but could somehow get starter money from a desperate team. DESTINATION: The Sixers have too many guys who need the ball – Andre Iguodala, Jrue Holiday, Evan Turner – so it is possible he may be moving on. Cleveland and Charlotte have a ton of cap room and need backcourt scoring.

12. BRANDON BASS: Always solid off the bench, made the most of his chance to start this season with career highs of 12.5 points and 6.2 rebounds. The 27-year-old has had a solid postseason as well and has a player option he can exercise to upgrade his $4 million salary. A bit undersized for the 4-spot, will never be a double-digit rebound guy and and needs a true center alongside him. But his 18-foot range makes him intriguing. What does Carlos Boozer do that Bass can’t? DESTINATION: The Celtics tried to get younger with Jeff Green and struck out. They can’t let Bass get away. But if he does, Washington would be a good fit alongside Nene – if the Wizards can clear out Rashard Lewis and/or Andray Blatche.

13. JAMAL CRAWFORD: The former Sixth Man Award winner, now 32, has a player option that allows him to duck out on $5 million for next season and pursue bigger money. If so, he will have to act quickly because he got left holding the bag prior to this season. He can still score with the best of them but his .384 shooting – his lowest since his 2000-01 rookie season – is cause for concern. DESTINATION: The Trail Blazers have a very unsettled backcourt and the ability to do some manuevering this summer. Crawford might be a better option in Chicago than Rip Hamilton, although the Bulls would have to get a bit creative.

14. JASON KIDD: He will turn 40 next season and has said he won’t play for the veteran’s minimum; maybe he doesn’t know what assistant coaches make. Getting by mostly on smarts these days, but still prepares and competes like hell. The ideal role would be as a 10-15 minute backup to a younger, quicker point who could set an example in the locker room and do some on-the-job coach training. DESTINATION: If he lowers his asking price, he could be an interesting addition in Chicago, where he could keep the seat warm for Derrick Rose and hold C.J. Watson’s hand. The Clippers, Celtics and Nets also make some sense. Then again, he might just retire.

15. NICK YOUNG: Until he improves his shot selection, defends better and puts the high school hijinks behind him, he will be viewed as a backup. But the 27-year-old can score in bunches – as he showed on occasion in the playoffs – and he does have 3-point range. DESTINATION: The Clippers have a handful of guards – Young, Randy Foye, Mo Williams, Chauncey Billups – potentially in flux. This is one they should keep at no more than mid-level money. He could fill a hole in Minnesota as well.

16. CARL LANDRY: Is he a starter or a sub? As a starter in 28 games with Sacramento at the end of 2009-10, he averaged 18 points per game. He’s been primarily a sub since, even though he continues to score in double figures and shoot above 50 percent. Landry is only 28 but probably at his ceiling, and he’s not getting the $9 million he got this season. DESTINATION: He could be on the move if the Hornets go big in the draft. Whichever team unsuccessfully chases Bass could use Landry as a consolation prize.

17. MICKAEL PIETRUS: Although his exit from Phoenix earlier this season was not exactly cordial, that has been his only career stop where he did not contribute to a winner with his defense and 3-point shooting. He gave Golden State a boost in 2007, helped Orlando reach the Finals in 2009 and now is giving Boston a lift. Now 30, he is not a starter but can be an effective wing reserve for the next 3-4 years. DESTINATION: The Celtics have been a good fit, but so would the Knicks and Nets.

18. RANDY FOYE: Has averaged nearly 12 points and better than three assists per game since entering the league six years ago. Will never be a knockdown shooter but has 3-point range (career-high 127 this season) and makes his free throws. Still just 28 and may get better in the right situation. DESTINATION: Could be the odd guard out in Lob City. The Mavericks, Thunder, Blazers and Wizards all have a need for Foye’s skill set.

19. BORIS DIAW: Clearly needs to be in the right situation, as his apathy in Charlotte and his enthusiasm in San Antonio demonstrated. But his all-around offensive skills and ability to play multiple positions will make him attractive. Now 30 years old, still doesn’t defend very well and his days of making $9 million are over. DESTINATION: Would love to stay with Spurs given his kinship with fellow Frenchman Tony Parker. The Heat and Lakers would not be bad fits but are limited financially.

20. TIM DUNCAN: It’s just so typical of this lifelong slacker to shake off a handful of subpar seasons and step it up in a contract year. What a bum. (We’re joking, folks.) It will be interesting to see how big a pay cut he takes from $21 million to keep the Spurs flexible. DESTINATION: It’s San Antonio, or the golf course. He said as much earlier this week.

OTHERS: Chauncey Billups, G; Raymond Felton, G; Gerald Green, G-F; Jeff Green, F; Jordan Hill, F-C; Antawn Jamison, F; Andre Miller, G; Ian Mahinmi, C; Steve Novak, F; Delonte West, G.

TOMORROW: Top 10 restricted free agents

Chris Bernucca is a regular contributor to SheridanHoops.com. His columns appear Wednesday and Sunday. You can follow him on Twitter.