I like some of the fighters abilities, but what the class lacks is depth. The champion is the baseline, and it acts like an anchor to hold other subclasses like the battlemaster or eldritch knight back because it would be bad if those subclasses overshadowed the champion to a great degree. But more importantly what I have always wanted for a fighter class, that no edition of D&D has ever presented well, is flexibility of choice that is currently present with spell casters. I want the fighter and other martial classes to be able to learn or gain more maneuvers just like a caster can gain or choose new spells. Once all classes have access to a toolbox of abilities I believe the playing field will be more level. But that is tradition versus trying something new and original argument, and 5E did not take that path.
I think what you are describing is called a Paladin or a Ranger in 5E: a fighter with a fairly reasonable number of spells. But to gain the extra spells, he has to give up his 4 attacks per round at higher level. Pros and Cons. Giving too many maneuvers (or more spells) to a fighter would make him like a Paladin or a Ranger versatility-wise, but he would still be dishing out nearly twice the damage at high level.
One also should consider that making Fighters too good (and as per this thread, a lot of people think that they are great), would really minimize the use of Rangers and Paladins in games as the "subpar" fighter types.