My ideas:
Judge- Tank
Uses a gun hammer, Garlean armor and rules cards similiar to Astro.
Soldier- DPS
Wields a gunblade and ceruleam manifestations like regula's tiger.
Magitek Pilot- DPS or Tank
Pilots a prototype suit of magitek armor built by the ironworks. Uses a mammot core, and has ceruleam weapons. It would be physically smaller and more streamlined than a reaper.
Summoner- DPS
Get rid of the egis. Give us a real FF summoner with real FF summons....