In 2015, PM was a shadow of his former self and probably underperformed his reduced salary. But the Broncos had a monster defense, and they won the SB despite PM, not because of him.
I don't have the info in front of me, but in the Tom Brady era, the track record of highest paid QBs is dismal w.r.t. to winning the Super Bowl. As you basically explained it, if your QB is making top-4 money, there's not enough cap space remaining to field a complete, championship team. The last guy to do it was probably Peyton in 2006. Mahomes came close after the 2020 season.
If this trend holds, you can pretty much rule out: Packers, Cowboys, Bills and Chiefs (although the latter 2 still seem like top contenders).