I'm fairly well travelled. Lived in Tokyo for a bit. There's no perfect city. London has the best combination of all attributes, for me.
Have you lived in London and Sydney both, or are you just reading numbers off of Google and "best city" lists? Sydney is boring and in the middle of nowhere.
I'm from Sydney and yes lived in London, Melb, Auckland and Hong Kong. My main recollection of London was narrow streets. I think we like being in the middle of nowhere (geography, nuke missile target, conflict), surrounded by ocean. It is true, it's the one downside, it takes a long time to fly anywhere else.