I've been using Pair Domains since 2001 (when they were called pairNIC). Pair Domains makes domain management very simple, and they have a wide and ever-growing selection of top-level domains they're authorized to register. Prices are reasonable, and I never get a hard sell from them (unlike other registrars I've had to deal with over the years). Their privacy tools are straightfoward too and don't require any extra charge. I have about 30 domains registered through Pair, and I would never change.

Pair's support team is first rate. Responsive and knowledgeable.