Hm. My advice would be to go with a Swordsage or Warblade, from the Tome of Battle: Book of Nine Swords, and just avoid the more complicated maneuvers. The martial adepts run similarly to spellcasters but also similarly to fighters. Instead of preparing a bunch of spells or having slots of varying levels, you just learn around 1-2 dozen maneuvers and about half a dozen stances, plus some very basic class features.
Gives a fair number of options but doesn't have to be complicated. The Tome of Battle has a description of Swift and Immediate actions (page 44) to explain how they work, which is fairly simple. At epic levels you could just multiclass into Bloodstorm Blade, a prestige class from the ToB. Epic Skill Focus could be taken at 21st-level to boost Concentration, for more damage with the Greater Insightful Strike maneuver. Or take Combat Expertise and Improved Trip (or Improved Disarm) later for synergy with the Warblade class features.
Ex.
Human Warblade 20
Stats: Emphasize Strength, followed by Dexterity and Constitution, then Intelligence and Wisdom
Human Feat: Power Attack
Character Level Feats: Cleave, Weapon Focus (Greatsword), Weapon Specialization (Greatsword), Melee Weapon Mastery (Slashing) *from Player's Handbook II* (or Adaptive Style from ToB otherwise), Vital Recovery, Greater Weapon Focus (Greatsword), Greater Weapon Specialization (Greatsword) *replace with Point Blank Shot if planning to enter the Bloodstorm Blade prestige class at 21st-level*
Warblade Feats: Ironheart Aura, Improved Initiative, Iron Will, Combat Reflexes
Class Features: Int bonus added to Reflex and various combat tactics, a few bonus feats, access to almost every Fighter-exclusive feat (as per a Fighter of level -2), Uncanny Dodge, Improved Uncanny Dodge, and can have two stances active simultaneously
Maneuvers: *1st-level* Moment of Perfect Mind, *2nd-level* Emerald Razor, *5th-level* Pouncing Charge, Dancing Mongoose, *6th-level* Greater Insightful Strike, Manticore Parry, *7th-level* Finishing Move, *8th-level* Adamantine Hurricane, Lightning Throw, Raging Mongoose, *9th-level* Time Stands Still, Strike of Perfect Clarity, Mountain Tombstone Strike
Readied Maneuvers: 7 (probably Moment of Perfect Mind, Dancing Mongoose, Pouncing Charge, Raging Mongoose, Time Stands Still, Strike of Perfect Clarity, and Mountain Tombstone Strike)
Stances: Punishing Stance, Stance of Clarity, Dancing Blade Form, Prey on the Weak
Active Stances: 2 (probably Punishing Stance and Dancing Blade Form)
Gear: Probably a magic greatsword of speed, magic mithral full plate armor (since it counts as medium armor when mithral), items to boost Str, Dex, Con, and Int, a ring of protection +5, a cloak of resistance +5, winged boots, and helm of teleportation. Or something like that.
Tactics: Pouncing Charge to run up and beat the snot outta stuff right away, then Raging Mongoose to beat on them some more on the same turn, then Time Stands Still followed by Dancing Mongoose to beat on them a heck of a lot more on your second turn, then Strike of Perfect Clarity for a big hit on the third turn, and Mountain Tombstone Strike on the fourth turn just to make anything left standing cry about all the Constitution its just lost. Standard action atack with swift action to recover maneuvers, then rinse and repeat.