Some people seem to think tsunade is as strong as Minato
Nah, Minato would be higher than Tobirama even though Tobirama has more experiences, stamina, physical strength and pretty great feats. I'm basing it by Minato being faster and better utilize FTG and can even redirect attacks with his barrier jutsus. Minato fought both A and Bee more than once (they were tag team partners) which made A say he thoughts Minato would never be surpassed and at the mention of Minato, Bee trembled (chapter called tailed beast bomb around the end of the chapter). A was alive when Hiruzen was Hokage so he should have knowledge of Prime Hiruzen. Plus the manga theme is the next generation surpasses the next and Minato is the youngest generation of all Hokages, I don't think Minato surpassed Hasirama since Minato died before reaching his prime but he can give him a good fight and out smart him if need be.
Hiruzen, when he died, was stated to be the strongest of the kages by Kabuto and Orochimaru in part 1 (Ohnoki, A, Mei (maybe since the 4th Mizukage was being controlled before Naruto them ran into Zabuza and since Obito didn't have the 3 tails and it was seen free, that means 4th Mizukage died), and Gaara's dad were the kages at that time). He said if he was 10 years younger then the fight with Orochimaru may have gone differently but Hiruzen was 13 years younger when he was fighting Kurama with Anbu black opts, Jounins and Chunins and he fell in the anime for being too old. If Hiruzen died at 69, was 56 when Obito attacked which is 2-3 years older than current Orochimaru and Tsunade age then Hiruzen Prime might around his hight 30's to low 40's. But we're not calculating Prime Hiruzen who was never showed so he would be below Minato.