All of my domains are with GoDaddy.
At work, we have about 30 or so with Register.com. Only two of them are on their “primary” servers which means if I make a change they are supposed to update the server within 15 minutes. These have 1 hour TTL time. The rest are on their “Free” servers which can in theory take up to 47 hours to update (both update once every 24hours 12 hours appart).
The only reason why the corp is with them is due to some of the other country support. Otherwise, I would move them all over to Godaddy.
At $43 per year for the privledge of Register.com… I’d stick to Godaddy.