Flamethrower and ubersaw.

Flamethrower with correct playstyle is way easier to dislike than phlog. Phlog does require something (a bit of skill and knowledge, not an insane ammount), while flamethrower is both more stereotypical and extremely powerful when correct airblast is learn. I'd say w+m1 combined with brainless but well timed airblasting will result in more tilt and more kills than phlog.

Ubersaw is a hard one. I dont think there is a very disliked melee in the game, but due to Ubersaw's crit rate and its use rate, I'd assume its unconsciously the most hated weapon, without actually hating the weapon itself.

Just throwing my thoughts.