Personally I like to play at PokerStars. I like the room and the competition is good with decent structure. Usually, I play from $4 - $50 tournaments preferring Deep Stacks events because most players do not know how to play small pot poker online and it's relatively easy to accumulate chips.
As far as promotions go I stick with PokerStars and FullTilt due to the bonus setups. I haven't had to deposit in years but I still prefer those two sites for my taste. Also, I live in the USA so it's limited over here.
Do or Die Poker