Those are deathstreaks, not Tier 3 Perks.
OP - I like using Sit Rep if I'm with a team to warn about mines, portable radar and trapped packages. If solo, I'll run Marksman or Stalker. I usually do a defensive perk in that slot.
One "tactical" perk to enable faster/better gun use.
One "defensive" to help me avoid traps
One "what's needed" to get the job done.
Slight of Hands
Come around the corner and level them.
Shottys and SMGs I run Steady Aim
Snipers and LMGs I run Marksman
ARs is when I change it up a bit. If I'm playing a particularly campy team I run Stalker. It lets me run through their claymores and usually puts me in a better position since I can walk through doorways ADSed. If the other team is more aggressive then I'll typically run Marksman
Assault rifles stalker so I can strafe and win gun fights then here them say wtf lol
Smgs steady aim or sitrep now.
Every class has assasian as I can't do well all the time without it yeah you get the odd game but mostly it's a spy plane spam
1st perk scavenger I don't die after every kill so I need ammo to get to an agm ect
Secondary stinger- team player and it brings my streak closer.