Twice was pretty good, but Dabi is the only villain left with any sort of emotional stakes. And Number 6 had a fantastic end to his character arc, by defying AFO and finding meaning in his existence through Koichi, and the realization that his interactions with Pop were genuine and actually had meaning to him. Similar to Dabi, but Dabi will probably not get as satisfying an ending because he will have to job to Shoto, doesn't get to face off against Endeavor for some reason, and probably can't even be given the dignity of suiciding by cop, because him dying means he wins. But, at least he gets to look like a cool fire zombie while doing so.