Personally, I prefer a truly villainous protagonist, one that adheres firmly to firm logic and doesn't bend their will towards one thing or another due to emotional states, only based on what they genuinely view as the most logical conclusion.
For instance, I am currently doing a small (Very small) piece of writing where the protagonist is a robot - not a human reincarnated as a robot, not an android, not a cyborg-turned-full-machine, and not any form of memory inheritance - just a flat out robot with a straightforward goal to become stronger.
He (I say he and use he/him pronouns, the robot has no pronouns, I just write wit he/him better) is direct, logical (To me), and takes the most efficient course of action possible, and has already killed someone in the first chapter because, instead of arguing with them for an item they owned, killing them would be the most efficient course of action.
But you do you - Just know, if your going for villainous, go hard - because, if I'm like anybody else on this website, I don't like a protagonist that can have their ambitions bent 180 degrees in a matter of minutes worth of speeches.