Hmmm, Well BulkRegister management fired almost all their employees and CEO last year. So I am not to sure about them. Their top management team is the same as Alabanza, which is a Hosting Company. I prefer my registrars not to be hosting companies. Also there has been a huge drop in customers, they are leaving like crazy. There whois server can be down for a 24 hours at a time before coming back up.
enom seems rather good, However they don't list name servers in their Whois (ICANN Rule) and they have bad error checking on other data there too.
NetSol is NetSol. (I actually still use them for some of my domains, it you have more then 50 domains it may be the cheapest price you can find). Layed off 400 employees.
Dotster is really good. I like them, however their price is not what I like.
Registrars.com was rather funny, last year were talking about how they would rule the world and be number 3 by next year(1 year later, they are gobbled up by NSI and they are all laid off)
AWRegistry went belly up, then some of them started SnapNames a year later. A lot of customers were very angery with AW.
Register.com, (sudo-monopoly). They think they are NSI so they act like them. Problem is NSI is losing customers left and right with their attetude and Customer Service and pricing. Register.com will slip form #2 to #3 by year end.
GoDaddy, the up and coming Registrar. They are open source software powered. But I have seen a few anger customers complain about credit card billing even after they had transferred out. These guys are the fastest Rising registrar.
Tucows, The new big kid on the block. They are really up there. They will be the number 2 registrar by year end. They listen to their resellers. They laid off 100 employees.
INWW, they are concentrating on pleasing huge corporations. Their big PR thing is that Yahoo is their customer.
Did I miss any?