Sturmtiger is clearly the superior.
Sturmtiger - AVRE
Range: 40 - 35
Damage: 580 - 440
Vet0 HP: 1280 - 1080
Max vet HP: 1440 - 1080
Armor: 220/110 - 290/180
Max vet Armor: 242/121 - 290/180
So clearly sturmtiger is better since it can almost 1 shot an allied tank. Also it has auto nade ability and as for the reload with vet the sturmtiger reloads on the move too. Given the option of 221 in the commander, it needs to be nerfed since now you can spawn a sturm and KT easily all you have to do is make 2*221.
