OK, here's a very, VERY boring test I did: I spent some time watching the 200-400 level at PokerRoom, PokerStars and UltimateBet. Here are the results:
PokerStars: 17 hands
UltimateBet: 11 hands
PokerRoom: 9 hands
Of course this is not 100% exact, but it gives me enough to make my choice. I'm just gonna wait for my
absurd bad luck to stop killing any chance I have of becoming a decent poker player.