You know it's too late to fix your reputation when people don't take anything you say seriously
When played to the maximum potential (best players, optimum vetoes, continual picking of most powerful strategies and commanders in every situation, every dirty trick used and abused (ghost wiring and sandbagging, truckpushing, etc), I'd guess Soviets for 1s and 2s. You could quite feasibly always go guard motor every single game OR shock rifle every game and reach top 20, and if you actually picked shock rifle or guard motor depending on the situation, go all the way to the #1 position, I think.
I'm not saying soviets aren't strong, but op asks for overpowered faction, which currently none really is.
There is no a single IWIN strat, there is no a single IWIN unit, OKW struggles first minutes against M3s, but thats pretty much it in the early game. Even USF isn't OP against Ost like they were last patch and soviets aren't stomped into a wet pulp by OKW bulletproof infantry, so yea, not really anything particularly OP this patch for the moment.
There are some whines here and there, but 3v3 and 4v4 heroes with rank position looking like a phone number who rise these whines aren't exactly the most creditable sources to determine what is OP and what is not.