First 76mm Sherman and T34/85 are both doctrinal, so you have to choose to get one of them.
Nope that is incorrect. One can choose out of 22 commanders.
Both have pretty much the same combat role, cost and timing while T34/76 differs a lot at all three criteria (including the fact that it can't go toe to toe vs a PZIV unlike the doctrinal choices).
Yes but one choose a commander with five abilities, one does not choose between T-34/85 and 76mm
You see? It really makes no sense to compare to T34/76. I know that you know that by yourself, why even saying that?
Once one chooses a commander one has to choose between building a stock unit or a doctrinal unit. So one does choose between T-34/76 and 76mm or Vanillas sherman and 76mm if playing USF.
In live 76mm Sherman is very effective tank with very fast firing Gun with ROF at vet 3 of 3.26 and can even fire faster with radio net. The unit does deserve a nerf either on base stat or on vet bonuses.