I've been using Gandi for years and can highly recommend them. They have great user interface that doesn't get in the way and waste your time (as opposed to GoDaddy, which at least back in the day when I was using them would be showing several pages of worthless "offers" you had to decline every time you wanted to just renew a domain name). Gandi also has excellent and easy to reach customer service (although I didn't get much chance to interact with them).