I really have no certainty on what I plan to do since I want to see how the game works first.
But off the top of my head
1: MA/HA grunt ( Depending on how infantry battles stack up.
2: Engineer / Medi (depending on which has toys I like better)
3: Lightning driver. Seriously I fucked so many people over with lightnings and loved being able to be a one man nuisance army
if not that then i'll probably tank it up.