[Not2B]

3 vs 3 = good

-More rounds
-More teams
-You get field time with almost everyone
-Broken robots result in 2 vs 3, which isn't the end of the world
-Scouting is different, not harder. (You need to be more creative, and data driven - at least it worked for us.)
-More exciting, IMHO, than 2x2 (but that's not a good reason for or against)

3vs3, 2vs2vs2, or 2vs3 would all be fun.

(2 vs 3... with an uneven field... and you get equal number of matches on 2 as you get on 3. That would be wild.)