Having travelled in A380, B787-9 and B787-10 in First. I'd say the A380 is more spacious and the cabin is much larger which gives a nice feel. Two toilets too. And more cabin crew which makes it more relaxed.
The 787 has a smaller fuselage and consequently feels more compact. Lastly the A380 is a lot quieter, there is less noise from the air supply and less noise from the airframe.
The A380 electric blinds are great, the 787 electronic ones IMHO aren't.