Rank the first perks according to how useful they are.
1. Scavenger Pro - Resupply from dead enemies. + Extra mags.
Useful if you use a lot of ammo, using a gun without much ammo, or shooting down enemy air support.
2. One Man Army Pro - Swap classes at any time. + Swap classes faster.
Even though it replaces your secondary, this allows the use of any default or custom class, perfect for adapting to the style of gameplay your enemy uses.
3. Sleight of Hand Pro - Faster reloading. + Faster aiming.
Very useful for guns that take long to reload, and the Pro part allows you to aim faster, and this can come in handy when picking off guys with your sniper.
4. Bling Pro - 2 primary weapon attachments. + 2 secondary weapon attachments.
I see this as a waste perk, as I use the iron sights on all my guns, but if you want to use thermal on your sniper but FMJ to make sure you get one shot kills, or like using red dot sight to obtain better accuracy, it's a good perk.
5. Marathon Pro - Unlimited Sprint. + Climb obstacles faster.
Only really useful if you're tac-knifing or rushing, and that can be done without this perk. Plus tac-knifing is noobish. Don't do it, or I'll find you.