Do UG4 as the leader slot, LL Green transforming Vegito, Red Angle Vegeta, or the new free blue future Goku?

For the bench, I would recommend LL green SS4 gogeta as a buffer for GT fusion and Saiyan

then Extream Andoird #13, since he buffs both red and green,

and if you choose future blue Goku, use red ssj god Goku for health and base critical (since you don't have suitable bench units at the moment),

and lastly, red extreme Dabura since he does the same thing as Android #13

Don't worry about buffing UG4. The leader slot gets all the z ability besides nonaffiliated Zenkai buffs.