I currently only own one domain, and it is through 1&1, got it for a great price. The only downside is their customer service are non americans, its hard to understand some of them, and they arent very friendly
I definitely use NameCheap and Enom. I love the easy use that namecheap provides and the quickness. I once got a brand new purchased domain site online in 5 minute. It was so sweet. I really like how they organize everything and how I can easily transfer money from paypal to namecheap without any long hassle.
I think I might be getting mine at netfirms.com they're only $4.50. If not there I'll be getting it at registerfly.com because they will be accepting paypal soon.
I only own 5 domains. 1 was purchased a long time ago at directnic.com, but has since been switched over to GoDaddy. All the more recent domains I have purchased were at GoDaddy.