When I first started in this I was using register.com, got tired of paying the higher price but they did have some nice dns tools (which I still miss) and their 800 number often came in handy.
I slowly, as they came up for renewal, moved everything over to directnic because I know the owner
I have had no problems with directnic (although I want them to beef up their dns tools a touch... doesn't effect me too much anymore since I set up my own dns servers)
I have never tried the really low price registrars because I believe you often get what you pay for out there.
I been bery bery happy with directnic
