Usopp easily.
The man has completely regressed since the timeskip with all traces of Sogeking completely gone from him, with one of the worst offending moments of his decline in character occurring in both Wano and Dressrosa where he chooses to run away and abandon others, with Oda reducing him back to a selfish stooge for cheap laughs.
To add to that, his new magic plant fighting style just feels like a hollow gimmick that doesn't really compliment his sniping skills at all when compared to Fire Bird Star, especially since most of his plants can move or even float by themselves. Incorporating seastone ammo like he did with his seastone handcuffs that one time felt like the right way to go.