It sounds, broadly speaking, that most people just want to see more interesting options available to fights as a core feature of the class, not a subclass trait.
Agreed. But the problem appears immediately.
Again I feel like LevelUp does this pretty well.
So you made this a '+' topic which limits my ability to disagree without feeling I'm stepping outside the bounds, but since you are the thread owner I'll risk it to say that I disagree completely. To me the 5e LevelUp fighter feels very much inspired by the 1e Pathfinder fighter that treated the problem as just "The Fighter didn't get enough toys" and in particular treated the problem as "The fighter didn't get enough distinctive class abilities". And a design that treats those things as the problem looks very different than a design that treats the fighter needs more interesting options that are NOT siloed as subclass traits.
In effect, the LevelUp fighter expects you to make multiple subclass decision both at CharGen and as you LevelUp. And this to me never will address the problem with versatility between the martial classes and the spellcasters who can essentially every day or every level choose to reinvent their build to meet new challenges simply by altering or increasing spell selection.
At both 1st and 2nd level (and again at 6th level) for example, you make one time choices in what your character is good at. While not everything is silo'd you are constrained by the either/or class feature silos. The elegance is not there. And to make matters worse, they split what I described into two classes creating a Marshall class as well, which additionally silos a lot of being a smart or charismatic fighter off into a whole other class.
I'm a bit skeptical of the 'Stamina as Mana Points' system as well. I am somewhat neutral about that in as much as a good implementation could exist, but a lot of the implementations I've seen are simply just giving up and making martials as spellcasting class.
I agree with people saying weapons need more differentiation that fighters can take advantage of, too. One of the "forgotten" benefits of the AD&D fighter was they could learn any weapon and if you used the full AD&D rules that was a big deal: weapon speed, reach, vs armor, etc..
There is an even bigger problem with how the D&D fighter has evolved over the years that this touches on. Not only do I miss having a reason to switch between a light weapon like a longsword and a heavy weapon like a morningstar or mace, but prior to the fighter becoming defined by a one time choice in weapon specialization (yes this problem does date back to the UA) a fighter adventuring could use any magical item he found. If he was using a +1 flametongue longsword and he found a +4 broadsword, then "upgrade". But if a fighter is defined as a guy who at 1st level commits to being good with specific gear or specific styles of fighting then the fighter is defined as the guy who is dependent entirely on finding a "christmas tree" that is decorated exactly how his build needs. Class features that increase specialization and increase gear dependency don't IMO actually address the problem. In fact, the real 'solution' would look like more the reverse - other classes that aren't fighters can only be good with a limited amount of gear - while fighters are just good with everything that has to do with fighting. If you look at the fighter pre the idea of specialization, that's not far from what we had. Most classes had to choose from a very limited selection of proficiencies. Fighters had a generous selection. Specialization actually starts creating the problem, not fixing it.
tl;dr As soon as you say, "Again I feel like LevelUp does this pretty well." I feel that you are saying you don't actually want a complex fighter.
PS: To end on a '+' note, one thing that I do think LevelUp gets right is that it is necessary to overhaul the system on a bigger scale than just rewriting the fighter. For instance, I do like that the maneuver system becomes the combat system and to a large extent every class is participating in it - it's just the fighter does it better.
