I'm a Registerfly refugee whose domains got moved involuntarily to a combination of GoDaddy and eNom. GoDaddy is cheaper than eNom for domains, but is relentless with the upselling on every purchase. They're also overpriced on add-ons like anonymous registrations. Enom is slightly higher-priced on domains, but is not in-your-face pitching other things to buy every time you do a transaction there.

I've had customer service contacts with both over minor issues and the experiences were equally good.

Between the two, I'd give a slight edge to enom.