Another vote for Namecheap. Although GoDaddy is also a reputable domain registrar except that their prices aren't as low. I mean $12.99 for a .com renewal with Godaddy when you can get it at Namecheap for $10.69. Also Whois Privacy Protection is quite expensive with them as well, that's if you need one.
I can only second all the comments about not joining them.
I have been their customer for quite a while and have rarely experienced a slower and more complex user interface than theirs. Their pro-SOPA attitude and their chauvinistic commercials are also not exactly appealing to many customers, let alone their ceo proudly slaughtering elephants in Africa (http://www.huffingtonpost.com/2011/0..._n_843121.html).
As many already pointed out a more than viable alternative is namecheap.com, which has a good customer service and decent fees, respectively I recently discovered nameѕilo.com, which has an even more straight-forwarding pricing structure and fast support responses as well.
I have used Godaddy in the past, and I must say that my experience hasn't really been the best. I switched to Namecheap though, which imo is way better. So I would suggest Namecheap. Lower renewal prices and less hassle.