The books I've generally been using are:-
Gamebookers.com - Brilliant selection of matches, choices, decent odds, and a nice layout.
Betsafe.com / Expekt.com - Two Nordic bookies, that share the same layout, and owned by the same company. They almost always have the best odds.
I've never had any problems with both of them. The only annoying thing is Gamebookers charge a small fee for withdrawals, but thats dependent on certain things (can't remember what)!