1. Saitama
Love his blunt nature. Despite his lack of emotions, he is actually one of the most emotionally mature characters. His convo with Garou is great
2. Flashy Flash
His and Saitama's interactions are comedy gold. Though I myself don't even know why I like him this much, I just do.
3. Garou
The best antagonist in the series for one, but I also really liked his character arc. Especially the conclusion.
-- Gap --
4. Tatsumaki
5. Amai Mask (Webcomic)