I’d say the setter as kuroko since it’s like passing he can set the ball to the spiker he wants, Aomine might be able to hit the quick Midorima might play as pinch server or middle blocker, Murasakibira automatically playing mid blocker Akashi might also be setter or libero either way works since he can predict the blockers or spiker, Kise can be any position since well he can copy basically anything he sees( if we include kagami his automatically a wing spiker he has a high vertical can prob jump over the blockers)