[naphand]

That depends what you are looking for. My experience was that UB $2/$4 was the tightest post-flop game of any site at that limit. Of course I was playing UK time and it was a few months ago.

UB players were much better post-flop, still quite a few loose players, a few very LAG players but typically weak-tightish. A raise means you are in trouble, a 3-bet and you are almost certainly against the nuts, or a total nut. The games are very beatable, you just won't see many big pots without a LAG or two on the table.

PS $2/$4 is more aggressive and stupid loose. Pick your tables and the games are pretty soft, but they play fast and loose. More varied player types so be sure to work on your reads and take plenty of notes.

My preference would be the Stars game, due to the higher aggression and lower trickyness. You should play the UB games as well as there is something to be learned from playing those games (controlled aggression being one).