Recently I've used Directbet mostly and I'd give it a 4.25.  It is very honest, which is great, but I find it a bit of pain to get the address for the bet, send it there, and make sure it's confirmed.  Then, you never know exact odds you'll get until it's confirmed, so something could happen in the match quickly and you'd be screwed.  The odds would reflect it, but it might not be the bet you wanted to make.

Anonibet 4.5
Nitrogen 4.5
DirectBet 1. Takes a lot of steps to get your bet in. The odds are just awful. All the BTC books that have failed were run by one person.

Anonibet -2