Wetworks: Wetworks users get protection against the wall-penetrating Promethean Vision Armor Ability. You’ll still show up on the HUD of a player using it, but you’ll be a slightly more inconspicuous outline rather than a big red blur. Also, you’ll get a bit of sound dampening when you sprint.
Pioneer: A good standby if you’re looking to rank up fast - this Spec generates extra XP for any action you take while you’ve got it equipped.
Engineer: As an Engineer, you’ll be alerted to incoming weapon drops a couple of seconds ahead of other players, increasing the odds that you’ll get their first. If you’re close enough, the HUD will point the way with a GPS arrow.
Tracker: Damn near killed yourself reaching a drop, only to find that it’s stuffed with underpowered guns? As a Tracker, you’ll have one chance to re-roll the contents.
Rogue: Players of SWAT in Halo: Reach should prioritise this one - its Stability perk reduces scope wobble while zoomed. I dread to think of what DMR diehards will achieve with the thing.
Stalker: A class for those who hold grudges. The Nemesis armor mod generates an icon of the last person who killed you, and also tracks those who’ve attacked you.
Pathfinder: Only the biggest guns will do? Sign up as a Pathfinder for reduced cooldown on vehicle weapons, and easier carrying of emplaced guns.
Operator: The Wheelman mod grants your ride a little extra resistance against EMPS. It also lets vehicle health recharge a bit faster. Fortunately, this latter bonus can’t be stacked.
----------------------------OP’s Choice------------------------------------------------
I’ll definitely have to go with Wetworks. Quick and lethal assassinations, reduced sound when active, and increased resistance to Promethean vision is the best way to go for quieter and less aggressive players on the field like myself. I like taking the quieter route.