Quartz
Hero
This is a redo of the Champion, right? I'm impressed. However... 
The Fighter needs abilities apart from the ASI at levels 4, 8, and so on, because the other classes get abilities (typically spells and spell progression) at those levels. Why not move Warrior's Grit to those levels? See also Action Surge and Second Wind.
Similarly, an additional ability are needed at the 5th level because the other combat classes get additional bennies at that level. How about Indomitable 1 / short rest?
I don't like Action Surge being moved to a Long Rest basis. Keep it as a Short Rest feature. And basing it off Proficiency Bonus means it's too good if you allow multi-classing.
Similarly Second Wind should be on a Short Rest basis and is a bit anaemic. I would change it to 1d10 + double your Fighter level once per Short Rest. And twice at later levels.
Too many Fighting Styles. How about limiting them 3 but giving enhanced benefits at later levels?
Not a fan of Final Blow. How do you know if an enemy has fewer than 100 HP? And 'dies automatically' rather than 'is reduced to 0 HP'?
The Fighter is inferior to all other classes, save possibly the Monk.

The Fighter needs abilities apart from the ASI at levels 4, 8, and so on, because the other classes get abilities (typically spells and spell progression) at those levels. Why not move Warrior's Grit to those levels? See also Action Surge and Second Wind.
Similarly, an additional ability are needed at the 5th level because the other combat classes get additional bennies at that level. How about Indomitable 1 / short rest?
I don't like Action Surge being moved to a Long Rest basis. Keep it as a Short Rest feature. And basing it off Proficiency Bonus means it's too good if you allow multi-classing.
Similarly Second Wind should be on a Short Rest basis and is a bit anaemic. I would change it to 1d10 + double your Fighter level once per Short Rest. And twice at later levels.
Too many Fighting Styles. How about limiting them 3 but giving enhanced benefits at later levels?
Not a fan of Final Blow. How do you know if an enemy has fewer than 100 HP? And 'dies automatically' rather than 'is reduced to 0 HP'?
The fighter is my favorite class, I love the fiction about them, but the class is inherently dull.
The Fighter is inferior to all other classes, save possibly the Monk.