I was thinking, we hvae so many different mission types and once you have done them, you will stick to the ones that are best for xp/time etc, which for most is either inflitraton or assasination, plus those are less likely to be bugged. Now my suggestion is instead of having them just for xp alone, doing a mission of a certain type helps build stats along those lines too..
e.g
Mission Type: Infiltration
Upon completing the mission you get say .1 added to stealth etc, and it can help players choose missions to help buff that style of ability... it would give more meaning to the type of mission you choose.
With say assisnation you melee damage is increased each time , and so on....
other missions, like recruit, helps speed buffs or so on, but we can balance that out...
