I did not vote for fighter, because I think that once we are set on a idea of a high level fighter, it will resolves itself: fighters are not lacking in power or mechanically advantages, they are lacking in theme and in-setting reasons.
Instead I voted for:
Ranger: Contrary to the fighter, the Ranger is lacking in mostly everything. The theme isnt well defined: a half-caster? A mundane survivalist? Defends the wild from civilization or defends civilization from the wild? Furthermore, its spells are bad, they do not have damage boosting feature ala Paladin if you do not want to use your spells as spells. They override the entire pillars they are supposed to be good at instead of being really good at it. Its a mess. Oh and also: the weapon techniques from the Hunter should have been modular options for all martial instead.
Monk: Much like the Ranger. They need to spend a semi-restrictive resource just to keep up with the rest of the martial character. Their archetypes arent balanced in the slightest. Their theme is both Cliché and Passé: its belongs to my father's kung-fu movies. There's a definite place for martial artist, but kung-fu panda meet ninja turtles meets kill Bill is not it. Their martial features could be given to all martial as modular options. If you need a full class for ''unarmored/unarmed fighting'', you are doing unarmed fighting wrong, just like you dont need a grappler class.
Druid: not weak per se, but wildshape is over-valued for non-moon druid. Its design space, which occupy a large portion of the druid's progression could be used for something more generally beneficial.