So, your argument on this always falls back to three or so tanks that are problematic to you, the type, pz, and 76i. However, I would say they are more the exceptions that prove the rule that premium tanks aren't OP. For tier 8 premiums alone, you have the WZ-111, IS-6, 112, FCM, CDC, Panther 8.8, STA-2, JT8.8, Lowe, KV-5, T-34, Super P, Type 59. Arguably, none of those tanks is what I consider OP. Several of them have preferential MM, which is a boost to winrate because you don't ever have the bottom tier issue, which limits your carrying ability, but that's primarily it. These tanks are the money maker, both for players and WG as they're expensive.
The Type 59 is a bit different. Its slightly stronger, but still not OP. Also, tier 8 mediums as a whole are meh. Many of them don't inspire great tales of play, and all get severely outclassed by the excellent tier nines. The days of the Type abusing people are in the past. Its now a tank with a reputation that's beyond its actual performance.
The other two you mentioned might be slightly op, but they are so rare their influence is minimal, and they are at tiers where balance is much more fluid. Tanks like the KV-1 can dominate at tier 5, especially for good players.
This game isn't plagued by such OP tanks. You rarely see them, and their OPness is overstated, I think. They don't single handedly annihilate teams.
However, I don't have the statistical acumen to pull this off myself, but to demonstrate your point, what you'd need to do is look at players with some of these OP tanks (large sample size of them) and then do an analysis of the win rates in those versus their average winrate in all other tanks. My guess is the difference would be less than 2%, and most likely significantly less.
A lot of the tier 8 premiums with pref mm seem OP because they have very high skill ceilings, but are often always top tier. Even at worse they have good mm spread. I'd rather play my IS-3 nearly any day, but I know my low point games (feeling like the bottom tier) are significantly less in the IS-6. And I'd take my KV-4 Amy day over the KV-5, too.
So, in short, you cite three tanks out of a collection of dozens of premiums. That's more the exception than the rule, and in addition, there are a handful of normal tanks that could probably be found to over perform for players, too, but since they aren't premium, they don't get the same attention. These tanka may be marginally OP, but that doesn't make the game pay2win. Small, relatively inconsequential instances of it don't damn the whole game and its hundreds of other tanks, which mind you, perform just fine.