I'm really sorry that I missed this thread before- I actually love all the answers so far <3
I love lengthy, messy redemption arcs that take themselves seriously.
Protagonists who fall into grey morality territory and have done genuinely nasty things- not simply a token mistake from some moment in their youth or childhood that nobody could seriously attribute to personal fault- but truly awful choices that cost them dearly (this really goes hand-in-hand with the first one).
I'm a sucker for "character refuses help out of pride but ends up failing or making a mess of things and realizing they can't go it alone" plotlines.
Also edgy, brooding types bursting at the seams with barely-concealed existential angst. I love them.
(If it sounds like I'm describing a single character arc with all four of these- that's because it's probably true...)
Ah, but wait- I do have something different- the lovable badass aka. a character who is actually quite affectionate and sweet but can turn into "the determinator" at a moment's notice when someone hurts the people close to them. Could be because I basically surround myself with people like this irl x')