The biggest benefits of Godaddy are
1. Market Share - most endusers have a godaddy account, or have no problem signing up for a godaddy account to do an account push. 60 day transfer lock becomes less of an issue. Most of my domain sales end up in someones godaddy account. Second I would say is networksolutions which most corporations seem to prefer.
2. Domain Discount Club - even without coupon codes. DDC gives you the benefits of being able to buy godaddy expiring auctions names cheaper, initial regstrations cheaper, and renewals cheaper than most competitors. Sure you pay the annual fee, but with coupon code for DDC, and a decent size portfolio, it more than pays for itself and you still come out on the better end pricewise.
3. Godaddy transfers out are QUICK. Unlike some other registrars that might take 7+ days, and again frustrate a buyer in a domain sale.
Godaddy frustrates me very often, my biggest issue is how it only occassionally remembers my default registration settings and nameservers, but the benefits now that I have paid for 3 years of DDC membership are why I am moving domains back in to godaddy. If you are a domainer, you have to have a godaddy account. Its pretty much unavoidable.
NameSilo is great. I just sold 2 domains today, and both are being transferred out of godaddy and back to an endusers godaddy account.
I also like Dynadot alot.
Godaddy, Namesilo, Dynadot and I will give uniregistry a try, but I'm probably going to end up consolidating most of my names at Godaddy for the convenience of dealing with endusers.