[MENTION=15700]Sacrosanct[/MENTION] Bravo

[MENTION=6867385]Paul Smart[/MENTION] I've been tinkering at a
substantial change to the fighter, but my quick and dirty changes would boil down to two things:
1) At 2nd level (when most classes get 2 features*), give the fighter the ability to
Shove (i.e. push 5-ft or knock prone) either 1/turn for free on a hit or as a bonus action. This would help differentiate fighters early on compared to other "fighting types" (paladins & rangers) who also get Fighting Style and Extra Attack, and it would more consistently differentiate them than Action Surge (which does a great job...but comes into play less often).
2) Create new subclasses with stronger themes (as an option in addition to the ones in the PHB). Like Mike Mearls pointed out, some players like a little more to hang a concept on than "simple fighter" or "complex fighter." This would be where the outside-of-combat features would appear.
Do those two things, and I think a fair deal of the disagreement around the 5e fighter would diminish.
*EDIT: I'd also advocate giving the rogue a little something at 2nd-level too; I'd recommend something like "Decipher Script" to play up their exploration role & the old "Read Languages" feature from AD&D.