Seriously? The sound in the O2 is miles ahead of Wembley Arena, something to do with the fact that they had U2’s sound manager work with acoustic engineers to reduce any echoing.
https://london.fandom.com/wiki/The_O2_Arena
Wembley Arena has to be the least comfortable larger venue in London; tight seats, a narrow concourse and the stickiest floors of any venue I’ve ever been to. I’ll suffer it under duress for bands I really wish to see if it’s the only choice.
Best London venue by a street is the Royal Albert Hall.