and decent support (i.e. not having to wait a day for response to email/phone).
I actually use half a dozen registrars for different reasons and in 16 years I've only ever had to contact two of them for assistance therefore my experience with that is somewhat limited!
The majority of my names I keep at Joker using a reseller account but have never needed to contact them. The one US registrar I had very quick service from a few months ago was DomainDiscover. I told them I was transferring the few domains I had there since they were more expensive than Joker however they matched their prices immediately.
123-reg in the UK never even responded to a query however fortunately I eventually worked out how to use their diabolical control panel.