My fifth tank?

Fonsyfun, on Oct 15 2011 - 17:53, said: I wont pay gold for another space, and I dont need it. I still have one empty slot, and what shoud I place there?
I dont have theese tanks but Im want them: IS-7 heavy tank russian, VK 2801 middle of the german tree light, Jagstiger tank destroyer german and Object 261 russian SPG.
But I still have a empty slot, what shoud I put there? The only thing I dont have is a medium tank so my question is wich is the best medium tank in the game? All around tank.
Edit: Also tell me where in the tech tree it is if you have a suggestion.