I started running COSMOS missions lately. Theyare pretty cool and unique compared to regular Security agent missions.
Of course, as I heard, you can not fumble with any of the missions, because they are one time only and failing them gives negative standing.
I found this awesome COSMOS mission guide while doing the research and I have been doing them in that particular order.
Thus far I have completed missions for these COSMOS agents:
I'm not going to detail about those, as I have already forgotten that stuff :P