Sorry i don't hate on Tsunade, but i'll try to go logically. Sure Tsunade is strong, but i think you underrate GREATLY Akatsuki members. Akatsuki is formed by the most powerful ninjas we have in the world, and that's something people always forget. Majority of Akatsuki members have already shown they are kage levels or even more for some of them. A kid like Deidara for example(who admitted that Sasori was even stronger) defeated Gaara(a Kazekage) in his own desert without even trying to kill him. People are bringing the fight between Sasori, Sakura and Chiyo, but they forget 2great things. Chiyo is the one who taught Sasori how to use puppets, so there are certain things that only she could knew concerning Sasori, also like she said herself, Sasori decided to die intentionally. I also believe Hidan is underrated. He has shown great subtility in close range combat with his scythe, he is clearly dangerous in this compartiment of the fight and since he only needs one drop of blood to kill the ennemy, Tsunade is in danger. Remember that Hidan even defeated a Bijuu by himself
That been said, i'll begin my comparisons:
Hidan VS Tsunade- I thought before these recent chapters that Hidan was stronger, but since we know now that Katsuyu can regenerate Tsunade even if she is cut apart, i will say it's 50-50 or Tsunade winning high difficulty
Konan VS Tsunade- Don't exactly know why people think that Tsunade wins obviously. Konan is difficult to touch with her paper ninjutsu, and she can make herself explode, so she is dangerous for Tsunade who is a close range fighter, but again i will give it to Tsunade high difficulty
Kakuzu VS Tsunade- Kakuzu has his doton domu to protect himself. He has powerful ninjutsus that could overwhelm Tsunade(even kakashi and his Sharingan had great difficulties to dodge them), and after that, he proceed to take her heart. Kakuzu mid difficulty
Sasori VS Tsunade- Tsunade needs preparation to develop a counter poison, Sasori is just a bad match-up for her in an actual fight(Sasori mid difficulty)
Deidara VS Tsunade- Deidara also is a bad match-up since he fights out of her range and uses explosiv bombs, so Deidara mid-difficulty
Kisame VS Tsunade- If Kisame uses waterdome, she can still use katsuyu to create diversions or get out of it. I don't see the waterdome as an issue. In taijutsu i believe she can tank his punches without problems. To absorb ninjutsu with Samehada, Kisame needs to go in close combat and i believe Tsunade could win. I say Tsunade high difficulty
Itachi VS Tsunade- Not sure why people say Itachi would win easily. We've seen in the recent chapter that even if Tsunade is cut apart, she survives and Katsuyu can regenerate her. She fought Madara without falling in a genjutsu, so i suppose she knows fighting against that, but even if we suppose she is caught by a genjutsu that she can't counter, what will Itachi do to kill her? Even if he cut her, she survives and with the pain, the genjutsu will even be broken. Tsunade could finish him in close combat if he is near at that time. But what seals the victory for Itachi here is that he can seal her with totsuka, so i'll give him(Itachi) the match mid difficulty thanks to that
Nagato/Pain VS Tsunade- I think that Tsunade will have great difficulties to handle Nagato. He has all the 6paths power. Just to handle Shinra tensei won't be that easy. We've seen that her Byakuyou seal could not support the Chou Shinra tensei, and after that Nagato still has a lot of jutsus. He can even remove her soul with human path. I'll give it to Nagato low difficulty
Tobi VS Tsunade- Tobi low difficulty because of Kamui