I've had no problems with these companies after years of use:
SRSPlus (as a reseller)
The least expensive, best UI, most perks, and best opposition to things like SOPA has been IME the Namecheap option. They usually are the cheapest and are always among the cheapest of the options, too.
I also don't remember Namecheap ever reserving a domain for registration only through them after I did a whois lookup through their web interface. Network Solutions (NSI) did that until ICANN told them to stop. SRSPlus is part of NSI so that's a strike against them.
So IME I can recommend a few, but mostly Namecheap.