I do plenty of 777 flying and did LHR-LAX on the 380 last month. Although newer, the planes and service felt similar. The negative, as CIHU pointed out, is disembarkation. On both sectors I was on the upper deck and both at LHR and especially LAX, the lower deck doors were opened first. That's a real pain for immigration queues and I had to beg to go down the staircase as I had a connecting flight in LAX. So for me, I'd choose 777 for those reasons only.