I played all 3 games, Shovel Knight, Hollow Knight and Shantae Half-Genie Hero and while I'm a sucker for fanservice, Shantae is my least favorite.
The game asks you to re-re-re-visit old maps way too much, and the dance mechanic turns cumbersome after a while because you need to transform just to cross some obstacle than transform back because your animal form sucks at combat.
Gameplay wise I think Shovel Knight is the best one (challenging and sometimes even a bit puzzle-y) however Hollow Knight is SO pretty you just want to explore a bit more to see how the next zone looks like.
Shantae game is pretty but can't compare with Hollow Knight, even with her dancing in a sexy ninja outfit. Hollow Knight just ooze style.
I think Shantae formula is a bit outdated now, the transformations need to something seamless which you activate on the go, like Megaman X dash, not something I need to bring a menu to use.
And please, tone down (read, remove) the backtracking.