I got to admit, it is both weird and refreshing seeing a FT character get some respect on here.
I think Tousen and Gin beat him though. Latter's bankai is a insta one shot and Tousen can remove his senses
That is the thing. FT is not a weak verse. It is actually pretty strong relatively and has a lot of hax. It is believed to be weak because people bash and downplay it to oblivion due to the writing being trashy at times. Feat-wise, it is up there
Natsu could counter Tousen's bankai with AOE
You are right about Gin's bankai but I doubt he uses it right away. Natsu is bloodlusted. He kills him before he can use
I'd say he stands a decent chance against most Captains below Tousen and Gin. There are some exceptions, for example I think Byakuya at his best would stand a pretty good chance of winning. Mayuri can win as well under the right conditions.