Two friends and I recently went to NJ/NY for a vacation. It was partially work related, as I needed to obtain my visa for China. We spent three full days sightseeing and shopping and were completely worn out when it was all said and done! So, here's my two cents on these cities (of what I saw):
NJ - much friendlier people, with a sense of community. Congested, but not as bad. We pretty much just slept here. We commuted into the city for tourism stuff.
NYC - a craziness like no other. Most people are ok, but there are a few rude ones. I guess you'll get that everywhere, but these ones seemed to be much more abrasive. I enjoyed the sights, but not as much as I had thought I would. It is a great city, but I've been to some pretty amazing cities over the years. And after going to San Francisco recently, nothing seems to compare. lol. No, in all honestly though, I enjoyed the city, but there is NO way I would ever want to live there. At least not in the city like that. If I could build a little house in Central Park, I'd reconsider. :)