Dump all the riding feats. You won't get to use them all that much IMO.
(fighter 1) Power Attack
(Character 1) Cleave (this feat is AWESOME at low levels)
(human) Weapon Focus - Greatsword
(fighter 2) Combat Reflexes - extra attacks are more damage. You get to make them while you are flat footed, so I prefer this over improved initiative, it doesn't matter if you win or lose the initiative, if enemies who beat your initiative try stuff on, you still get to make AoO against them. With your high dex you get up to +3 attacks every round, so you could in theory get 4 a round.
(character 3) Iron Will - with wis of 8, your will saves totally suck, I think you really need a help here. I might go for BlindFighting instead, and just accept that you will be held etc, blindfighting really helps land those hits against hard to target opponents.
(fighter 4) Weapon Spec - Greatsword. Obvious really.
With your stats, I would personally swap the Dex and Con. Unless you get mithril armour your high Dex will be mostly wasted (you won't get to make that many extra attacks of opportunity generally). Who knows what magical armour you will be picking up as the campaign continues, high con give you more HP all the time, no matter what.