Depends. However the finest stacks were certainly those Chosokabe with 10-12 samurai archers with 121 accuracy and quick reloading and some monk archers protected by a mix of Naginata and Katana Samurai clad in fine armour with some highly experienced monks and cavalry thrown in. The DLC unit pack was not out yet as those 175 range Samurai would have been also handy.

I invaded the the mainland with 7 or 8 Samurai and Monk stacks. 500000 koku in the treasury and a huge cash flow helped to sustain that military power long enought for the ultimate victory.