Pinnacle is far and away the best, but they don't give service to Americans.
I like Matchbook. Has the best juice of any lines out there. Problem is, they take a 2% commission. So the reduced juice is offset by the commission.
5 dimes is the next best site for the reduced juice. However, they are a recreational book and will limit you if you're making too much money. Bet Jamaica and Legendz will do this too, Legendz has a minimum bet of $20.
If you're trying to deposit via Credit Card, the only book that has worked for me is Bookmaker. They also have very early lines. WSEX has ridiculous limits for NFL games ($20K). The Greek is very simple and has great halftime lines.
I care about books that won't limit me, have the least juice, high limits, and accept credit cards. Bookmaker fills 3/4 requirements, so that's where the majority of my bets are placed, however I wish they had reduced juice.