The Fuel per seat figures for the A380 (ie all seats occupied) over an 6000nm ULR are 8% worse than the 777-300ER.
The 777-9x and the 787-9 are both more efficient then either of the above. These new aircraft make it hard for anyone to buy and operate new A380's. The 787-9 burns 27% less fuel per km per seat than the A380.
A380 (3 class) - 3.16 per 100km (544 pax)
B777-300ER - 2.91 liters per 100km (365 pax) +8%
B777-9x - 2.85 liters per 100km (395 pax) + 11%
B787-9 -2.49 liters per 100km (294 pax) + 27%
If you can fill a A380 with pax - go for it, if you can't... park it and take a Boeing!