I don't think platformers got any better than Super Mario World honestly.
Games like Ninja Gaiden or Mega Man X added some interesting stuff like wall jumping or dashing, but I still think the sheer volume of physics possibilities in SMW's controls is just the peak of the genre and all devs can do from here is do things differently but not surpass it.
I think the only other game that I would consider more complex than SMW (strictly talking about controls/physics) is Mischief Makers with the jets and the amount of speed/trajectory variables, and of course also has the grabbing and throwing aspect (that can and does affect the platforming), but despite MM being amazing and honestly with an endless skill ceiling, I still think of SMW as the king.
There's a reason it's SMW that's the most popular romhack platformer game ever.
I've played more modern indie games that kind of embarace the kaizo culture, such as I wanna be the guy, vvvvv, meat boy, dustforce, they all are clear followers of old school platformers but I wouldn't necessarily say they are better or more refined than the old games, they just focus more on certain aspects.