>>528558917
Nah Mech is fine to play if you enjoy the playstyle, it's just that the OG resistance trio (WH, Mech and BaM) have been neglected for a long time, BUT they actually got good buffs in the latest KMS update while demon slayer got nerfed.
Realistically most classes will just bounce up and down the damage charts throughout the games lifespan, the only class you could say that the devs hate is Wild Hunter (if you ignore classes like Kanna that don't exist in KMS), who has pretty much been near the bottom of the list for most of the game's lifespan while being clunky as fuck to play despite that.

TLDR: So long as you don't pick Wild Hunter or Kanna you are probably fine.