Godaddy hands down. The best customer service always open even at 3am when I am bored and just want to talk to somebody and that is best security you can have.
The Security is just as good as the rest of the registrars mentioned above if not better, you see a few years ago some dude named Gordon Lyon had his site shut down by Godaddy and so he made a mock site called Nodaddy.com which he made a lot of domainers scared that this was happening all the time, which is FALSE.
What most people don't realize is that having your premium domains at Go Daddy give you the most eyeballs you can have on a domain to get end users that want to buy them.
My best advice is to get all the names you actually want to sell listed for sale in Go Daddy Premium Listings or you are missing out on potential sales.
No other registar can provide this the way Go Daddy does.
-=DCG=-
for whatever reason, whenever there is "domain news" in the form of stolen domains, ceased domains, domains or other "options" added to cart, no help recovering domains, etc., etc., godaddy is at the top dead center nearly each and every time.
Does anyone other than name.com offer this or something like this? https://vipmobile.verisign.com/home.v
Please do let me know as this seems to be the extra level of protection I am looking for now.
I've started using name.com recently and imho their website is outstanding - fast and efficient. $8.99 for dotcoms and free privacy. I'll be looking to put more business their way. If anyone wants to comment on their security and respect for domain-owner privacy in terms of the OP's experiences, I'd be very interested to hear about it.