Donya Fortress for me.
Scrapmetal is next up, I love watching the train go by. The lighting is fantastic too.
Operation 925 is my least favorite, it doesn't seem to have a lot to offer and I run into more campers here than any other maps.
Operation Firestorm is still my #1 map in the game.
Currently playing MGS2 (360) and Super Mario 3D Land (2DS)