If you've got a lot of domains or are willing to pay their crazy retail prices - Fabulous.com. I've been with them for many years and have hundreds of domains

If you've got a lot of domains or are willing to pay their crazy retail prices - Fabulous.com. I've been with them for many years and have hundreds of domains with them. Best service and feature set I've experienced (and price, but I am not sure you will qualify). They've had the features other companies are just 'launching' for 5+ years. I can even see things like how many times people are hitting my WHOIS lookup for a domain (go ahead, copy that feature, it's awesome). They have free privacy and can setup all sorts of authentication to change domains if you want to add that level of security.