A bit of both I'd say. ;)
Kind of depends on who you romance though.
Adriel = MC is always the more dominant partner.
Grigori = Player's choice if they want to be the dominant or submissive one.
Barghest = They like to alternate, but MC is mostly bottom in their relationship I'd say.
Jason doesn't have any NSFW scenes as of yet, but I imagine human Jason being a top, so MC would've been bottom in their relationship when he was alive at any rate.