4 knights since the game would become more tactical
4 bishops or four knighits.

i'd say bishops have them all developed in the right places you could cover nearly the whole board while knights you have to re-route to the other side of the board.
So I would say Knights.
Try and make it closed.
If you can't, then you have always got your queen or rooks to go to. You would have to use them a lot more.

First instinct is knights, because bishops would be clumsy during the first part of the game.
But you should be able to trade off at least 1 set of minors easily. I think I'd go with bishops.
Normal, or
4 rooks, 1 knight, 1 bishop.
At first it seems great- more rooks!
But I think it may be more complicated... I'd go normal.

If it's 4 bishops vs 4 knights, the knights will actually have problems getting active I think. And any that do can easily be traded to where you'd have a normal 2 B vs 2 N kind of position.

Normal, or
4 rooks, 1 knight, 1 bishop.
At first it seems great- more rooks!
But I think it may be more complicated... I'd go normal.
When there are 8 pawns each rooks aren't worth a lot... but with so many extra rooks you could do 2 exchange "sacrifices" and have a normal position. So I'd take the 4 rooks.
BUT more importantly- how would it effect the way we play our beloved game?