I'd be interested in a neutral registrar, who wouldnt comply to random silly laws. Such as impacting freedom of expression, or who would not kidnap your domain.
Management, interface. I have been with some "small-time" regional registrars and some of the interfaces where terrible. Simple tasks become complicated (and sometimes impossible), often I found myself emailing them because their interface didn't have a certain functionality.
If this isn't enterprise production business stuff, it really doesn't matter. They're just selling a commodity. Go with the cheapest one.