As you long as you're using a major registar pretty much the only difference is price & included features.
1&1: - Worst support I've ever dealt with. Slow canned responses, every response takes at least 2 days, nothing gets fixed in less than 4 emails! :BangHead:
- Free whois privacy (private registration)
- Crappy & Hard to navigate control panel.. No bulk updating of name servers :kickass::BangHead::bangin::boozer:
- Free email address with each domain (*maybe* looks like a new feature)
- Convulted (purposefully misleading) domain cancellation process
GoDaddy:- Best Control Panel. Fast and user intuitive
- Support is okay, canned responses are a bit annoying though.
- Free email address with each domain
- Free hosting account with each domain but the catch is it's ad supported, so I skip that.
- Easy domain cancellation/deletion process
Worst part of GoDaddy is the upsells at every turn. It gets annoying after awhile
Name Cheap:- Easy to use Control Panel
- Transfers between users, super easy.
- Decent Coupon Codes
- Easy cancellation process
Cannot say anything about support, never had occasion to use it.
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Even though 1&1 is the worst on my list, I use them for most impulse buys as their the cheapest. If I don't develop the site, I can just cancel it and only loose $6.
All in all GoDaddy is the best IMHO.
Forgot to add another registrar above: Dreamhost, I had a couple of domains with them when I hosted there. Nice CP, free whois privacy, it's easy to set auto-renew options for each domain individually.