OxBill is No1
But a word of warning, only go with them for Non-Adult.
The reason why they had a bad wrap before is because they used Dingo for adult processing and not their own gateway (dingo the con artist from internationalbilling.net). Dingo screwed them like he did all his customers and that got passed onto their adult related clients.
OxBill is the best processor i've had in a long time, but use them only if its a non adult related site. Talk to Adam from OxBill, he has always been very helpfull to us.