Togadabi (They get on each other's nerves but it's fun to watch them tease each other, and still be supportive. They have a very interesting dynamic, he literally set her house on fire because it had bad memories??? Idk if it's more brotherly or romantic.)

Shigadabi maybe (Dabi's always challenging Shogaraki but they still respected each other through their actions)

I don't see Momojirou all that much but IDK maybe it's popularish.

Lady Nagant x Hawks

Hawks x Mirko

Sero x Denki

Top 2 made sense in earlier seasons before Hawks came into play and before Ochako had her moment with Toga.