As a passenger, if the choice is between a B777 and an A380, then there is no choice, A380 every time.
But in the near future that will not be the choice and its the near future this thread is about. It will be 777X or A380. The 777X is borrowing lots of technology from 787 and will be considerably quieter and more comfortable than 777. We'll have to wait and see if that means as quiet and comfortable as A380, or more so. If 777X exceeds A380 in that regard, what are the chances that the airlines will invest in their A380 to "catch up"? Especially if doing so INcreases the cost per seat-mile.