I think December is the most beautiful time to visit here. There are so many people on the streets of 5th avenue, shopping open late, comedy clubs, entertainment and of course, the tree is absolutely beautiful - no matter what religion you are, it s a beautiful time of year
New York City is geographically in exactly the same location all year, so geographically speaking it doesn t make any difference.If you actually mean climate or weather, it can be pretty uncomfortable in midsummer and cold in the winter. I d recommend early Autumn or late Spring.
Its always nice. Weather wise, I would say May-July. Good luck!