cloak and dagger is for pusillanimous individuals.
invisi-watch or dead ringer is the way to go.
I'm horrid at the spy though.
I can't for the life of me use cloak and dagger, I don't have the patience for it and it allows time for stupid stuff to happen to you.
It's the easiest to use, as you can sneak around the battle to get behind the enemy. It's only bad on 2Fort, as far as I can tell. I'll trade with you to give you one, as I have a dozen if you like.
Just add me on Steam.