I want to try a design approach, where the class has to select a fighting style at first level. Each fighting style will give benefits and grant feats that try revolve around a single ability score. This leaves us with 6 different fighting styles that all must feel iconic. It is my intention to grant other abilities according to what choice of fighting style is made. For example, the constitution focused style should get heavy armor and tower shield proficiency and maybe a bigger Hit die, while the dexterity oriented style rewards a less armored character with mobility and tactical benefits.
The 6 paths of martial fighting style is the following:

1. The Warrior. Strength oriented style. Favors two-handed weaponry. Utilize a direct and brutal approach to combat, with the ability to deal high amounts of damage in a few swings. I feel the style needs a way to sacrifice extra attacks in a meaningful way to gain a bonus of some sort that will make the choice between full-attacking and single-attacking relevant. Also, he needs a gap closer. A way get into the fray and start hacking and slashing. Maybe a leap.

2. The Guardian. Constitution oriented style. Favors the sword and board. Utilizes the shield in new ways to mitigate damage, while still trying to be an attractive target. Needs ways to manipulate enemies to attack him instead of his allies. Also, I'd like to give him a gap closer to step in front of an ally that is about to get charged. Also gets heavy armor and tower shields.

3. The Tempest.Dexterity oriented style. Favors two weapon fighting. Utilizes two weapons at once to both attack and deflect. Needs a way to deal relevant amounts of damage, while still having some mobility. Might have to sacrifice some damage to gain some mobility, but I'd like to have the choice be made by the character in the time of need. Gap closing could resemble tumbling around the battlefield with greater efficiency.

4. The Expert. Intelligence oriented style. Favors unorthodox tactics and weapons. Utilizes tactics like disarming and tripping to greater effect. Maybe get ways to use both in the same attack sequence. This is where I'd like to place a few debilitating debuffs, like blinded or deafened. Other styles might get debuffs too, but they need to be more prevalent here. Gap closing could be done with a grappling hook maneuver where you either pull in the target, or get pulled towards it.

5. The Archer. Wisdom oriented style. Favors projectiles and distance. Utilizes great range to wear down opponents before they engage in melee combat. Wisdom is used as a way to spot out the weak points even at range. Usually, this fighting style is a dexterity oriented style, but I feel that dexterity belongs in a greater degree to the dual wielding style, and wisdom still makes some sense as a primary stat for ranged fighting. Otherwise this style needs to become something entirely different. The wise warrior. But at the moment I can't find an iconic role that this style could fill, other that maybe a combination of the guardian and the expert. I don't want to go there, as I feel that the styles need their own identity instead of just overlapping.

6. The Warlord. Charisma oriented style. Favors midrange combat and boosting allies. Another unorthodox approach to a martial concept. This guy uses his allies to hit the enemy, all the while he is still making his friends look awesome. I want him to be an active player contributing to the party instead of doing it the bard way. Buff up round 1 and 2, then sit back with a crossbow and hope to hit something. This style grants allies extra attacks with special bonuses depending on what kind of choice the warlord made this turn. Granting allies extra move actions and such. Every party should want at least one of these guys, yet he must not get out of hand and become mandatory for every party.

This design approach will not demand the player to choose a fighting style at first level. Instead, it will give the class some choices each level that will allow the player to build a Fighter as he/she seems fit. These options should be spread out among the levels, so that a player has to make a choice or two at each level. They will choose among feat packages, special maneuvers and stances. Each option should resemble some ability that you can imagine a purely martial character to be able to do, and each of them should support a specific kind of build. But all of the options must be modular.
Thus a player can create a character that resembels and excel in 1 area of martial combat, or he/she can create a fighter that “dips” in each category to mix and match maneuvers to fit his/her character concept.

This approach will shift the focus on multiple ability scores to a single ability score focused class. Strength should be the primary drive behind this class.
This also means that many feats that are granted as class features should be granted without having to meet prerequisites. This will allow a player to focus on Strength, Constitution and whatever other ability score they may find attractive or relevant. Many feats will have to be reworded to benefit this approach. It doesn't a whole lot of sense to have combat reflexes and 10 dexterity.
The martial archetypes that needs/wants to be supported are the following:

1. Two-handed melee. Focusing on pushing through a lot of damage through swinging a huge two-handed weapon in wide arcs and great chops. Iconic abilities should include a way to hit multiple enemies with a single swing, pushing enemies around and knocking them prone.

2. Two weapon melee. Focusing on dual wielding two weapons and swinging left, right and center at the same time. Iconic abilities should include ways of hiting multiple enemies during the same attack action, moving while attacking and debilitating enemeis movement. Damage should be comparable to the two-handed melee style, but spread out among more attacks. This can become an issue when dealing with damage reduction, and therefore the class should have a way to penetrate such defenses.

3. Thrown weapon ranged. Focusing on getting some range between yourself and the enemies while pummeling with larger pieces of thrown metal. Should include iconic abilities that hamper enemies movement, increase your own mobility, throws while moving and ways to throws other objects (maybe even enemies).

4. Sword and Board melee. Focusing on using a shield to stand in the way of enemy attacks, while keeping yourself and your allies alive. Includes iconic abilities that reduces incoming damage, takes damage that are otherwised meant for allies, hamper enemies movement and making himself a more attractive target.

More to follow I'm thinking of including an unarmed combat style (please recommend more if any pops up).