Perk 1 - Use either lightweight if you like to rush or Hardline if you like killstreaks faster, BUT only if you run anything above a Guardian, or Flak Jacket if you find yourself dieing a LOT by grenades (see perk 3 for a reason NOT to run Flak Jacket)
Perk 2 - Use Scavenger to resupply your Black Hats (a MUST have for hardcore), and Betties (also another must have), or Cold Blooded if you die a lot to hunter killer drones.
Perk 3 - ENGINEER. Really there is not another perk that needs to be used in HC. This not only protects YOU from hidden equipment, BUT with Black Hat you can hack it through the walls and usually get a kill by the idiot camping behind it.
Here are the reasons for NOT using the other perks
Perk 1
Blind eye - you won't see very many killstreaks that are AI controlled in HC. I have literally almost 1,000 matches played and seen 5-6.
Ghost - There is no permanent radar up, so the ONLY time this perk is effective is when the enemy has a UAV up, so if you play a team that only gets 1-2 up a game then you are wasting a perk slot for ONE MINUTE or LESS of gameplay. If you carry a launcher you can literally shoot them down before the second radar sweep, AND you get points!
Perk 2
Hardwired - I have literally NEVER been EMP'd and the use of counter UAV is pretty well limited to players who get it in care packages, and even then most of the time they will re-roll it to try to get an assault streak.
Fast Hands - You don't see very many grenades, so the throw back reset is useless, and swapping weapons faster is not really necessary.
Toughness - You pretty much instantly die, so you will never have a "flinch" reflex when shot
Perk 3
Dexterity - this one I'm on the fence about, as if you had an extra 2 slots to use with the perk 3 greed, this one would be the one to use.
Dead Silence - really the only thing this counters is Awareness, and probably only about 5% or less of players use this.
Extreme conditioning - Only useful in HCKC, and not any other mode in HC
Tac Mask - useless perk as if you run engineer YOU CAN SEE SHOCK CHARGES, and not too many people run flash/concussion
Awareness - Unless you are dead set on sitting in a small area and waiting for enemies then there is no need for this.