I was in NYC about 6-7 years ago. It was probably different than now, but I didn't think Manhattan was dangerous. Just really crowded and overrated. The movies make it seem like this amazing, magical place and I wasn't feeling it.
I'm a Chicago native and it seems more dangerous in Chicago.
West Coast cities are the worst though, with all the homeless encampments, filth, etc. The West Coast has a lot of strange people too. Gets normal again in the rural areas.