My favorites are (in no particular order).
Courchevel H/L (Pot and No Limit)
Limit Omaha 8 or better
No Limit Hold'em
7 Card Stud 8 or better
For tournaments, I will play HORSE, and even the 8-10 game mix (I have some understanding of all those games). It's quite amusing to read the full string of responses, and to see that one person's room of choice is UltimateBet. I actually preferred Absolute Poker over UB.