Catherine. It looks softer and prettier. The 'K' looks too harsh for this name, in my opinion. A bit off topic, but I don't understand why the Duchess of Cambridge, whose name is Catherine, goes by "Kate" when she could have gone by "Cate". It kind of bugs me.
Yeah, really. I agree. And although I do prefer Katherine, one thing in Catherine's favor is that I like the nickname Cat, and if I wanted Cat, I'd definitely go with Catherine and not Katherine because I wouldn't like the initial letter switch.