Lets talk Fighters. What works about them? What would you change and why? How can they be improved?
The 5e version of the Fighter class is my favourite ever. It does exactly what I want it do i.e. be the best at non-magical combat, with enough unique abilities to set it apart from other martial classes, and enough room for differentiation within the class itself. It also has enough
narrative for me to be its own class, even tho it suffers from the old problem of the authors
not talking about it enough in the printed books.
If I could back in time and change something in the PHB Fighter, I would perhaps (but not necessarily) roll back to when Combat Superiority was a base class feature instead of Battlemaster only.
For instance, I would remove the 2 extra feats compared to other classes, and put Combat Superiority in their place (not necessarily at the same levels, which is quite late).
Why would I do that? First of all because Combat Superiority is IMHO one of the best thing in the whole game, and it's kind of missed when you have a non-Battlemaster Fighter. In fact, it's now creeping back into other Fighter archetypes (the Cavalier at least).
Among the PHB Fighter archetypes, it actually makes sense that only the Battlemaster gets Combat Superiority, because the Champion is supposed to be low-complexity, and the Eldritch Knight already has spells, and probably having both might be too much to manage.
But here's the second reason: the Champion is part of a failed promise to deliver low-complexity options for all classes (or at least for the "core four"). There is no low-complexity option for anyone else, just the Champion for the Fighter, at which point they could have just forget about that promise and ditch the Champion completely or give Combat Superiority to it too.