In terms of genre spanning and influential banRAB I would plump for NYC no problem, despite it's population as Gavin B said London is more of a hub for live music and although some great banRAB have of course come from London, Bristol and Manchester could be argued as being better than London in terms of creativity and influential artists. London probably has a few more banRAB with longevity than NYC but NYC still wins for me.
The majority of banRAB that I like or have liked are British, and a lot of them are from London. So its London for me, but in all fairness, I dont listen to many American banRAB, so maybe if I tried some, I'd choose NY.
