I've been to LA many times, and I just spent a week in NYC. We saw 5 fabulous shows in NYC, all within walking distance of our hotel. We hopped the subway several times to go out to Brooklyn, The Bronx Zoo and the Grand Central area. We never waited more than a few minutes for a train. And sitting in LA traffic doesn't compare to the speed of the subway. As a visitor, NYC wins for me.
That said, I would never want to live in NYC. It's a completely different lifestyle than I'm used to. The winters are too cold for my taste. I've always lived in the California suburbs (SF Bay Area). I like the freedom of having a car. I like the big, free parking lots when I need to shop. I live in a congested area, but people are spread out and not "warehoused" like they seem to be in NYC. However, my son has been living there for about a year and half and he's thriving. He loves the energy of the city and the fact that there's always something interesting to do. The theater scene is his thing and he's always entering and winning lotteries for discount show tickets. He's an actor who alternates between doing shows (all outside of NYC so far) and living in NYC, auditioning and working at his survival jobs. I really enjoy visiting him there and I'm glad he's happy and doing so well. But I'll keep my feet planted in CA.