Most of my domains are with Moniker, they are king as far as security goes. I'm also satisfied with Dream Host as a registrar, they have free privacy and it is super easy to transfer away from.
Hover.com is a new one that I've been hearing good things about and they are probably worth investigating.
Moniker has been just rubbish in terms of domain renewals. I gave it my PayPal and its automated emails said that yes, my domains are up for renewal, except they didn't and I almost lost them. It turned out that I needed to prepay in advance in order for auto-renewal to work. That's just stupid IMHO (they're not my bank) and clearly their automated system is wrong in what it thinks is happening.
Hover.com is a new one that I've been hearing good things about and they are probably worth investigating.