The least impressive so far are Luffy, Zoro, Usopp, Kidd, King, Big Mom, P1, Sasaki, Killer and the biggest disappointment is of course Crydo of the 100 hostages.
I didn't include Law, he's currently not part of the arc anymore. Same for Chopper but for different reason, he is the weakest straw hat, can't expect much of him.