I've never met a rude New Yorker. Sure, there are plenty in a hurry, but there are also a huge number who are happy to chat, I've found.
No significant difference between New York and London, in my experience.
Or perhaps that means that Londoners are as rude as New Yorkers, when viewed through the eyes of a San Fran Ciscan. (London and New York economies are closely bound together, they have a lot of similarities, so maybe that's the reality?).