I do like the main character to be likeable, at the very least relatable in their assholeness... That is not to say they have to be good, or even have redeemable characteristics, but at least give me a reason for him to be evil, and some more other evil characters to consider the antagonists.
But your milage may vary... I don't like main characters like Dexter or Light (mostly because they are far more evil than the antagonists, and never given a reason why should a root for them), but it is obvious many people believe they are good protagonists. Evil protagonists is an extended trophe (see Hannibal, Darth Vader, American Psycho, etc), but they never resonate with me, as I see them as the protagonist because the writer thought they are far more interesting than other characters.