I purchased "economy space" seats in advance on recent EY flights: EY101/EY100 return from AUH to JFK (A380) and EY406 from AUH to BKK (B77W) and am really glad I did. I didn't bring a tape measure to confirm, but I felt the leg room on the A380 to be a tad more spacious than the B77W. I will certainly continue to purchase these in the future as leg room in the back looked far too snug to endure for very long.