Don't underestimate the heat in NYC in the summer! It might be up north, but there's a LOT of metal in a confined area and the sun reflects off all the buildings which builds up the heat lol. Thank god for the stone ones, it keeps you from frying!
I live in NYC, and I love it. I'd say Disney only because I've only been once, BUT it also depends on the amount of time I have! I'd want to be able to go everywhere, do everything, so I'd need DAYS to feel like I saw enough at Disney. Depending on what you're into, you can do a sizable chunk of the city in a few days! If you do decide NYC, feel free to PM for tips and ideas!