Purely a L2P issue on your side. Virtually all good players agree that the T34-85 is the best (or at the very least top 3) medium. Its cost-effectiveness is through the roof since it is highly capable at fighting infantry as well as bullying other mediums. Its health pool also makes it a great choice for taking on the KT.
You might not realise that it has 800 health, more armour, and a lot more pen than the T34-76, but that really matters in tank vs tank fights. Statistically it has approximately a 90% chance of winning 1vs1 against an Ost p4 (significantly higher % chance to pen + 25% more health), which costs 30mp and 10 fuel less. There's literally no medium as cost-efficient as the T34-85.
Ost has plenty of counters to the T34-85, but that doesn't change the fact that the T34-85, in and of itself, is a top-of-class unit. If Ost had a unit that good, you and CODGUY would have quit the game already. Ost P4s already have a slight edge vs Shermans, T34-76s, and Cromwells, but the P4 still gets blown away by T34-85s.
The OKW p4 has high armour that gives it a very light repair burden and great survivability, so certainly an argument can be made that it's the best medium. But dissing the T34-85 simply means you're a really bad player who doesn't understand how incredibly cost-efficient the T34-85 is.
You are comparing a tank that is in a doctrine vs stock P4....