My top 3 list of overpowered heroes are, in no particular order: Zarya, Lucio, Zenyatta. I didn’t put Reinhardt on the list because I think he’s more than fine if he isn’t paired with Zarya and Lucio specifically. I’d put Widow in here too, but she falls under poor game design rather than numerical balance.
“tanks” are not overpowered. Zarya is just out of line. Her ultimate is too good for how easy it is to get, her energy mechanic is too easy to use and too forgiving to warrant such a high power level attached to it, and the strength of her right click far outweighs the ammo consumption of it, and the balancing factor of deliberately having tanks be close range.
Lucio is just crazy. Sound barrier is probably the second best ultimate in the game next to graviton, his speed aura is empowering tanks like Rein and Zarya to a level this game has not seen outside of Mercy 2.0’s synergy with Zenyatta (which, for the record, was also the ONLY THING that has EVER usurped Lucio’s must pick status in the near 3 years history of Overwatch). His personal mobility is incredible, and the utility of a four second cooldown knockback is nearly unmatched.
Zenyatta is the perfect example of how high a power level supports are really on compared to the other roles. He’s the second most dangerous target in GOATs next to Zarya, discord is the best non ultimate ability in the game (argues could be made that it contends with speed boost for that spot), and his cross map pick generating, burst damage right clicks are just so out of place on a support. And that’s before we even get into how fast he charges his ultimate because, unlike other supports, his primary source of ult generation is not healing, but rather damage. So unlike heroes like Ana or Mercy, when your frontline dies and you have nothing to heal, he will happily continue to farm 50% of an ultimate while his team is being wiped.
I left Brig out, because she’s just a mess at this point. She’s still a catalyst for the 3-3, but no more than Lucio or Zarya. The difference is that Brig is absolutely terrible and basically a throwpick outside of 3-3.
Oh, and OWL GOATs has been somewhat unimpressive so far. Several contenders teams have a far stronger GOATs than the average OWL team.