Agree with flyerco. Delta's 747 upper deck configuration (1-1) is the last of its kind, and will be retired here shortly. The space is second to none.
Only quibble is that the overhead lockers on the upper deck are slightly smaller than the lower deck due to the curvature of the airframe, but it's no issue--FAs will usually be happy to put your carry-on in a closet by the galley.
Delta's 747 1-1 upper deck configuration is also superior to their 777 product. I'm not a fan of their 777 product; it feels cramped and I don't like looking out onto the aisle. It definitely feels less private.