I think that large CA/CTF/FFA/TA public servers with teamsize votes disabled/restricted there and an appropriate map rotation would do the trick, cause if you're only half-decent it's far easier to frag better players and/or to be useful for your team on a 12v12 serv than it is on a 3v3 server. Ditto in FFA.

Also FT, ra3map11 and q3wcp5 free would be ideal. Perhaps Distant Scream and Overlord in a few months too? They're pretty much useless currently anyway.