I've been playing around with trying to design a Fighter based on unlimited use maneuvers...meaning, abilities that can be used situationally or with some kind of risk:reward mechanic, instead of X times/rest...but really so many of the good ideas (if not the best implementation) are already in feats. Charger, Mobility, Shield Master, Sentinel, Mage Slayer, etc....
So I guess all the feats that Fighters get can contribute to the idea, except that those things compete with ASIs, at least for a while.
So maybe a new, one line subclass is:
Warrior
Whenever you get a new subclass feature (at 3, 7, 10, 15, and 18) pick from Charger, Mobility, Shield Master, Grappler, Mage Slayer, Sentinel, Alert, and Dual Wielder.
By level 20 you'd have quite a collection of cool things you can do.
I'd happily play that subclass.