Yeah, I agree.

Game of Thrones may have a few straight up villains that are... maybe not likable, but awesome enough that their evil antics put a grin on your face. But GoT has so much going on with so many players that we never really develop the same sort of relationship we have with Francis. So yeah, pretty sure he's the greatest anti-hero since his character stresses the anti in anti-hero so much more than any other-- he's essentially only a hero in that our perspective makes him the protagonist.