My first room was Fulltilt, I think. I loved PokerStars although you really had to search around for loose tables; it seemed like it was overloaded with tight and rocky players earning FPPs. I played a lot on UB although I regret it now. I didn't lose any money to the site (just the players!) but if I had known how sketchy they were, even after their sale, I wouldn't have played there. These days I'm on BetOnline, and have a BlackChip account, but am considering Bovada or America's Card Room. BetOnline doesn't have many $5+ MTTs.