Light gray definitely! Pick one of the gray shades in your rug.

Check this, different paint shades http://stylecarrot.com/2012/06/07/montage-54-living-rooms-with-gray-sofas/

Maybe light beige

Also Check out the ideabook Modern Living Rooms - Contemporary Living Rooms from houzz.com

If you are going to pick a gray, look at grays that have a blue undertone like Benjamin Moore stonington gray HC-170 which is a light gray. Don't forget to test your color by painting poster boards and moving them around the room and looking at the color different times of the day both in natural and artificial light for a few days before committing to the color. Good luck -KM