Stars is the best for soft stud games, have played there for years. Ante is low, lots of newbie players.
UB has a solid micro HORSE game. Unlike most sites, the players stick around for all the games -- at some places people sit out all the time in games they don't like, which ruins things.
AP is also good for stud.
Myself, I've never had good results in ring games at Tilt, not sure why... Antes are too high for one thing.
I also find soft stud games at the Euro sites like iPoker network, Titan, Paddy etc.