Gimme the T34-85 and ill be happy. I love the speed and protection the T34 gives me and the 85mm would be the perfect addition to that. 
Adding another T34 wouldnt be worth while until the dmg model gets adjusted. I have yet to give or take a single hit to a T34's turret and not have it knocked out. Quite bogus.
IMO... there are other gaps that need to be filled prior to adding any more tanks. I think the Firefly could use a few more perk points, too.

Far too many of them are being used in comparison to Pzr 4 or T34's.