This thread does not have the Fifth Edition tag. I wish there was a Design tag so I could clarify what I was looking for.
My intent was to discuss from a design perspective how we could have martial classes that require the same amount of skill and coordination to play as spell casters while still feeling thematically like martial classes. How do we make fighters mechanically engaging while retaining a play environment where most the things they do are at will and spell casters still have daily spell slots, hopefully with individual memorization?
Basically I want to remove the tension between playing a fighter because I like them thematically and playing a psychic warrior or cleric in Third Edition or playing a paladin or cleric in Fifth Edition because they provide the mechanical engagement and challenge I am looking for. Fourth Edition lacked this problem, but fighters did not feel like fighters to me after awhile. So far it looks like Pathfinder Second Edition has solved this problem in one particular way, but I am interested in other possible solutions.
I am not looking to argue that Fifth Edition should be a different game. My criticisms of it are limited to what I am looking for. I am not entitled to anyone's creative labor. I play the games I want to play and do not give a damn about how popular they are. The kind of game I am looking for would probably not be as accessible as Fifth Edition needs to be. There is no harm in acknowledging that.
I do think there is some room for a more complex fully at will fighter and would like to see that. Not holding my breath. Just like I do not think we will see a fully competitive true Vancian Wizard like I would also like to see.
Personally I am not wedded to any particular version of Dungeons and Dragons. In the last year I have played Dungeon World, Fifth Edition, Moldvay B/X, and Pathfinder Second Edition. I am going to continue playing all of these. I probably will not run Fifth Edition. I do not default to Fifth Edition when discussing Dungeons and Dragons. As far as I am concerned there is no standard bearer. All those games I mentioned are just as much Dungeons and Dragons as any other.
The problem that I see is that there's not a lot of room for a fighter to grow into without stepping on spell casters toes. As you said, add the wrong style of powers and, as you said fighters stop feeling like fighters.
I think the best option (using 5E or 3.5) is to have fighter specific feats that allow you to chain maneuvers.