For me by far my best preformer is UltimateBet. They have great software, and do a lot of redeposit bonuses wich keep my players coming back.
Crazy vegas poker is a good on also, they give $10 free no deposit and a 33% rake back, this has givin me some loyal players that play each month. They are part of the prima poker network and I feel there software is terible, but that might be just me.
Partypoker is good also, if you can find any players that havnt already signed up. The rake the hell out of there games so it is a good earner.