I'd go with Warder. Free Combat Reflexes that works off of your primary mental stat (either Int or Wis, if you take the archetype for it, the "Zone of Nope", and a class that is pretty much built to work with a shield.
And what Feats should a character like this have? (Will not be playing a human)
Ordained Defender You lose Knowledge(Nobility) and 2 bonus feats in the switch.
For race, Ultimate Psionics' Duergar (with their Expansion ability, Huge at level 7) makes for an INSANE AoO area for spear/shield. 15' space, 30' reach, plus, if Zone of Nope going on an extra 5' + 5' per 5 levels of threat.
Pikeman's Training, obviously
Piercing Thunder Style - Creatures provoke when entering reach weapon's threatened space
Shield and Shield bash related feats
Extra Readied Maneuver (since Warders get so few)
Martial Power (-Atk for Temp hp, but only if you are usually forgoing full attacks, the -Atk will kill your iteratives)
Take the Blow (great for tanking, and a larger reach, covers more enemies)