I don't promote sportsbooks myself but if you're looking for the best quality then here are a few:
www.willhill.com - William Hill are one of the UK's top betting shop chains. I'm not sure if they have an aff program but you could email an enquiry.
www.ladbrokes.com - Another top UK land company. They have an aff program but you need to get approved and then sign some documents.
www.playboy.com - They have licenced the use of the Ladbrokes service so should offer the same high quality. They have an aff program, but i'm not sure if it's ready yet.
Can't really offer advice on any others - but these 3 offer the highest reputation and quality.
Craig Miller -
Casino-Help.com