The only one I haven't played was Iconoclasts.
Hollow Knight is really good, Valfaris is alright, could have been much better. Axiom Verge is also alright but I enjoyed Hollow Knight more.
HK's fairly moddable and has a few mods that change up the gameplay quite significantly in case you'd ever want to replay it with a twist.
Because it's not like every 2D game is the equivalent of Ubisoft's constantly rehashing the same game over and over again. 2d platformers play completely differently from each other and the biggest similarity they can share is that they're in 2d. Speed, momentum, gravity, level design, combat design, enemies, how you heal, what abilities you get, how those abilities tie into combat, how they tie into movement, how movement and combat can be merged together or isolated, all of that differs from 2d game to 2d game.