Alpha cons can be low Hp and energy reserves.
Jungle Hunter 87
Cons: none.
Pro: most balanced stats overral
Zerk
Pro: extra melee damage I guess, has more Hp
Viking
Pro: same as zerk but more perk points.
Sam
Pro: extra melee damage, ghost spec, Hp I guess
Scout
Pro: fast, high stamina, high perk points, disciplined spec
Alpha
Pro: pretty much same as Scout but 2 less perk points, extra melee damage, assassin spec.
Valk
Pro: decent speed and stamina, ghost spec
City:
Pro: high energy, decent speed, stamina and hp. Analytic spec.
Elder:
Pro: high energy, Stalker spec, perk points, gear points


