i just switched to http://www.gandi.net/, i wasn't able to find a single bad review.
Before that: NetSol who are crap, JumpDomain who were worse than crap, and Joker who were OK enough.
It's a little bit more expensive ($15 vs the usual $10 a year) BUT it has a great interface. And you get free private domain registrations, which I think is worth the extra $5/year.