I loved the Silent Cartographer. The beautiful beach, impressive level design, Covenant to slaughter. What's not to love? Or if I feel like sniping, I'll play T & R on heroic or legendary.
Oh Btw, what was the hardest battle on legendary? For me it was the part just before boarding the T & R. A lot of people have said it was on the T & R. But I found a little trick which is to wait in the rooms that the Covenant pop out of and pick them off from afar. Cowardly but effective.