If looking to T-34 M41 (I believe) with 76L41 F-34 cannon, it is more powerful than Sherman M4 - M4A1 75L38 cannon, if there weren't any special ammunition used, and as I recall, M4A1 or M4 didn't use tungsten rounds.
So all in one, pretty much equal guns.
T-34 M40 had lower velocity cannon (L-11), weaker than M4s.
I figure that T-34 M41 would be quite fearsome anti-tank.
M41 came on same year as M40, with more armor also I believe.
To have equal year T-34 as PZ-IVh, it should be T-34 M43, which I believe is fall/winter '42 and with more armour again, but same F-34 cannon.
T-34 with 85mm would be quite a monster, but it wasn't done until something like mid '44.
US M10 Wolverine would be quite intresting, with fairly low armour and open top, but with 76L54 cannon.
For online play in Main Arena, T-34 M43 would be good choice because of its speed, though, totally lacking self defence when having only coaxial and bow machineguns.. (maybe issue them with PPSh 41G so they can try their luck

)
What comes to Pz-IVhs A-A MG34, I'd be happy to see it work like that!
I never wasn't sure of that it would go around like that, so I kept shut.. I hope that its muzzle gets smaller also. (its fairly huge even though it should have flash hider making muzzle effect smaller)
Other that I'd like to see would be anti-tank guns to be pulled with halftracks. (of course this would disable use of troops, because AT-gun crew would be there)