Let's see...
My default character is usually a selfish rogue sort, if I don't have any other big plans.
The other go-to tends to be grizzled vet types. "War is hell, I've seen some shit" kind of thing.
I don't tend to play happy characters. Mostly, they're deeply unsatisfied with... something. Themselves, their situation, like, society, man. Whatever.
I do tend to play PCs who've been doing their deal for a while, whatever it is. The whole fresh-faced, newly Awakened/Embraced/knighted deal doesn't really appeal to me. That's, like, the backstory.
I also really like playing wiseass sarcastic PCs, but what can I say. That's fun to me.
Oh, and I also tend toward morally grey at best sorts.
As far as other people's PC types... I mean, there's a few things that might get me to give some side-eye. Mostly the "really dumb, vaguely offensive stereotype" sort.