Hard to tell

UA747: upper deck is good in row 15, lower deck usually less crowded is ok in the back middle section

UA777: has the better cabin layout, seats are the same as UA747

LH747: has angled flat seats that I personally feel uncomfortable. I am 6'4" and the seat is short. Plus the lower section below your knees is again on a different angle, so that sleeping on the side hurts!!. Entertainment on LH is by far better, but no Channel9 !!