In approximate order of threatyness.1. DC United. This is admittedly a reach. United has undergone a radical makeover in the offseason, offloading attacking midfielder Freddie Adu and forward Alecko Eskandarian to bring in a bevy of offshore attacking talent. Brazilians Luciano Emilio and... uh... Fred -- not the "Fred" who is a
striker for Lyon and a member of the Brazilian national team, some other Brazilian who goes by "Fred" -- figure to get most of the playing time vacated by the departures, but England-born Nigerian U20 winger Kasali Yinka Casal is a promising youth player with gobs of speed who may push for time on the wing. They join Jamie Moreno, the second-leading scorer in MLS history, reigning MVP Christian Gomez, and fringe USMNT members Ben Olsen and Bobby Boswell.
Emilio is already paying off, scoring an array of cracking goals in the CONCACAF Champions Cup, and you've got to love a guy named "Fred." They're the pick, especially now that the Adu circus has taken itself half a continent away.
2. Houston Dynamo. Last year's champs return virtually untouched. The only player of even minor consequence gone is Canadian Adrian Serioux. Returning are Brian Ching -- the poor but upwardly mobile man's Brian McBride -- Chelsea-slayer Dwayne DeRosario, up-and-coming USMNT defensive midfield Ricardo Clark and, well, just about everyone who won the MLS Cup a season ago. Continuity is good, especially when you win and stuff, but the Dynamo's success in MLS' abbreviated and strange playoff system shouldn't overshadow the fact that they weren't the best team around last year and aren't likely to be this year.
3. The New England Revolution. The Revs go into their first full season without rapper-winger extraordinare Clint Dempsey, but he had lost interest in the domestic league after his breakout World Cup performance and wasn't having much of an impact towards the end of his tenure anyway. Perpetual Revs Taylor Twellman, Steve Ralston, and Pat Noonan return to form a trio with the league's strongest understanding of each other. They'll miss Dempsey but not as much as you might think. The rest of the team returns, as you might expect, intact. They'll be good as always, but it's hard to imagine the Buffalo Bills of MLS getting over the hump without adding an impact player from somewhere, anywhere.
The much rumored Denilson signing, recently thought dead, has been completed. The Brazilian playmaker is probably the best player to ever sign for MLS, Beckham hype nonwithstanding, as he is a former Brazil international and was a key substitute on the 2002 World Cup championship squad. He's also just turned 30 (today; happy birthday, Denilson), which is by no means young but also by no means over the hill. At one point he was the most expensive player in soccer history. Real Betis shelled out $40.5 million to pry him away from Brazilian power Sao Paulo in 1998. 
