Harest Armor to unlock in Halo 4?

As far as i know, the hardest armor to get might be Vanguard. You need to get Forerunner destroyer mastery, which basically means killing almost 1000 of each type of enemy in Spartan Ops. It might seem kinda easy, but when there are only 2-4 crawler snipers per mission and that you need to kill 1000, it gets kinda ridiculous. There is also Vanguard Converge, which is win 100 or 150 CTF games i think. I’m working on that right now.

What do you guys think the hardest armor to get?