Are they even worth using over ammo or dexterity? I’m close to getting stability which I can see being decent in long-range scoped DMR fights, however, if you’re fighting long-range you tend to run out of ammo as you don’t pick it up after you’ve killed someone.
Wetwork is nice, but I don’t find it that useful unless I’m camping in CTF or something which isn’t really my play style. Any comments?
Fast track
requisition
stability, are the only good ones to me
stealth is okay to boost assassinations.
Depends on how you pair the Specialization abilities with other stuff in your loadouts.
I use Fast Track with Double XP in Spartan Ops 
Helped me get to SR 107.
I think they all have their perks, but a couple are a bit situational. Gunner is fairly underestimated. You can strafe with the turret! It also makes mounted or vehicular turrets take longer to overheat, which is very useful in a Mantis.
My ranking of specs from best to worst imo:
Stability > Stealth = Wheelman = Gunner > Requisition > Drop Recon > Nemesis
Fast track does not affect gameplay.
It’s all situational though.
so far Ive only completed operator since I play mainly dominion and am an avid vehicle user, and let me tell you, that wheelman mod is awesome since everyone can spawn with the plasma pistol… if I’m in a wraith and some dude is able to EMP me, the effect is shortened so much now that I can easily get a mortar round into him well before he can recharge for another shot, or if I’m in a banshee and somebody luckily EMPs me out of the sky, usually I regain control just after I hit the ground, they have no time to hit me again…
I agree that operator and the pathfinder perks are very useful when you’re in vehicles, but how does stability help if you have to sacrifice a larger clip in order to use it, especially when it only really helps during scoped firefights which is primarily long ranged, you will run out of ammo…