Ghillie is the best in my opinion, that's why I chose it over Spec Ops. Although it offers less armour and space, the camo more than makes up for it. If you use the right arsenal and don't expose yourself for too long, you'd be very hard to kill. I mean would you rather have a tad bit more armour or would you want to be hard to spot?
I know this is weird from a Spec Ops user.