The 787 seats on Qatar are awfully cramped in Economy, or so I have read.
But if they are changing to the A350, then I think it would be better. I have not flown on Qatar, so I don't have first hand experience.
I've flown with Emirates in Economy. Pretty good.
Here are some video reviews. Emirates Singapore to Dubai on the A380.
https://youtu.be/-nXZM64tHXc
Emirates Dubai to London on the A380.
https://youtu.be/4DUkv4aihuU
The Dubai Airport is massive. But our layover was quite long, about 3 hours.