which would u recommend if I only have 5-6days in CD: CD + Emei Mountain or Jiuzhaigou + Huanglong?

I suggest you travel CD+Jiuzhaigou and Huanglong for a 5 to 6 days trip.

Jiuzhaigou Natural Reserve and Huanglong for 3 days(by air of course).
Other 2-3 days:
If you don't want to have a tight schedule, go for a city tour in CD City will be a great choice. There're a lot tourist spots, such as CD Panda Base, Jinsha Site, Wuhou Temple, Jinli Ancient Street, etc.
But if you do have enough time, My suggest is to go to Emeishan for 2 days. You don
t have to climb the mountain as it is so exhausted. They have cables and tour buses! And believe me, it's so nice if you can have a chance to see the sunrise at Golden Peak.