I've been happy with name.com. I like that their interface seems to let me manage my domains without "getting in the way" with too much other stuff. They're also sane on the anti-SOPA train and such, which does matter to me. I haven't used them for registration, but I am also using EasyDNS for DNS on some domains, and like them so far. Gandi.net is one I haven't used personally, but a ton of my FLOSS contacts are all googly-eyed about them.