I tend to use GoDaddy for .com, .net or .org
and for .co.uk I tend to use 123-Reg, although I've read a few bad things about them I've always found them very good, including support, maybe I've just been lucky!
I see they're related to FastHosts, the name that brings me out in cold sweats! Had some major problems with them on a recent client site! Saying that I've heard similar stories with 123-Reg hosting, it seems the larger companies can't do both domain registration and hosting to a good standard!
I have had hosting with GoDaddy, its fine for mass hosting, crap for speed and trying to navigate around their website is even worse!
I've bought 4 domains in the past 4 weeks with orderyourname, all through paypal, all instant and very easy to change nameservers/DNS settings. Only took a few hours to get it on different nameservers and IP which I was impressed with.
if you're hosting is on GoDaddy and you buy a domain on orderyourname then you have to change the nameservers and IP. They are both on the same nameservers so you need an exact IP to point to the correct server otherwise it wont link to oyur hosting properly I found out!
Not had to use customer support with orderyourname so can't comment, could be useless, but Ive had no need to even use them as of yet!
123-reg are good with customer service but for the price I prefer orderyourname.
The GoDaddy site does seem to be slower since they had their recent "re-design", and the advertisements for additional add-ons/services can be annoying, I think I've used them so much I just don't noticed them anymore and know where to click to make it as quick and painless as possible!
I'll check out Moniker next time I need to pick up a .com