Gyou'un no doubt lol. Gyou'un got the power behind his strike somewhat compared to Gaimou, who is being set up as the MC's big 1v1 for Wei. Rinbukun on the other hand has no such hype to compare him to Gyou'un.
I would personally take Gyou'un over anybody not named, Gaimou, Tou, Renpa, Houken, Moubu, The current 2nd top general in China the Tiger of Chu, Karin, the guy who held up Ordo, might be some more i'm forgetting but you get the point list is very short.
Essentially no underling can beat this guy, and even out of the generals only very few can beat him.