I would love to see DCS C-17. As stated before the more aircraft the better everything from cargo, tankers, and even civilian add to the entire experience. It will also entice more aviators to fill our servers.
Personally I'd love to see the HC-130P included into DCS especially once we're given multiplayer single aircraft multi-crew position capabilities it'd be the ultimate test of teamwork to accomplish goals. I'd have fun flying around especially refuelling the helicopters. That being said C-17 all day! Bring it.