In my experience balance is created or broken in actual play by the challenges presrnted or chosen in the setting chosen and gameplay by the GM.
Barring egregious degrees of out of whack (that rarely these days make it to print in professional games) the keys to balance comes from GM identifying and using the different strengths and weaknesses to let them be "balanceable" characters in play.
In my experience the fighter class is "balanceable in play" in my role as a GM. While not a fighter, the barbarian is a true force in play at my table. Fighters would be just as capable (and balanceable) depending on choices, in slightly different ways.
So, I cannot really comment on a generic "fix fighter clas" with solutions because the statement that some folks have some problems foesnt give specific complaints to address. To fix a problem, you need to know the problem.
But, as general rule, I think in part some broad sweeping comments have led me to believe that part of the problem is self-limiting. It seems like many of those playing fighters start from the perspective of every fighter choice must be made to emphasize optimized DPR. So, the idea of using the extra tests for non-DPR options, width vs power, seems often to be dismissed. This to me is illustrated when some of the suggested fixes involve adding 1-2 more skill proficiencies but depending one of the extra feats on skilled ( or the XGtE one) is laughed at.
I think all classes suffer when all your choices are driven towards damage. Nobody questions when a bard or cleric or sorc or wizard chooses a few non-damage non-combat options, but it seems the fighter class fixes often, not always, wont look at that possibility.
But again, while to me it is perfectly suited for balanced play, I would love to discuss specific problem that needs fixing.