It has been long proven that the best classes in TF2 are Scout, Soldier, Demoman, and Medic. These classes are also known as "generalist classes". These classes are well balanced and are a staple of any enjoyable gameplay (whether that be you or your teammates playing these classes). Without these classes, TF2 would suffer from poor design problems and boring stalemates. The other side called the "specialist classes" have nothing to prove but that they cause stale and unengaging gameplay.

Pyro: Designed to be a useless throw-a-way class. Best utilized as Engineer's good little puppy.

Heavy: So boring and linear that it would be unironically more enjoyable to eat a rice cake.

Engineer: Literally designed to cause stalemates.

Sniper: Unbalanced and a stupid design

Spy: Sad and pathetic.

Need more evidence?

Start maining generalists and stop being a detriment to your team.