If you didn’t check yet, you should take a look at GoDaddy Alternatives blogpost.
In quick resume, the best two alternatives that I found for registering domains are the following:
NamecheapThis is one of the cheapest domain registering services that I was able to find (with good quality, service and costumer reviews). They are not just cheap but they also include free WhoisGuard! How great is that? Way better than GoDaddy!
Domain.comIf you aren’t satisfied with Namecheap, you can also try Domain.com is probably the most known domain registrar in the world. You may check them out too and compare the pricing and service, but consider yourself warned, you have to pay for WhoisGuard/Domain Privacy in Domain.com. Still, a great alternative to GoDaddy.