I don't live in either, but NYC is denser, has more foot traffic. It's grid of streets, lack of alleys etc. hold few surprises. I believe you can fool around a lot with statistics.... and no matter what statistics say, the night feels more secure in NYC than in London. Also if you are used to a night out in Italy or France for instance, the Brits binge drinking problem creates an unsettling feeling for those not used to such a spectacle. I love London, but I'll take Manhattan over London any day...or night. ---