What kind of large breed dog would do well in NYC?

You want your dog to be your DOG, not your baby, that is where most problems start...not treating the dog as an animal, first.

Second, protection happens because the dog is bred, selected AND trained to protect, not because of ANYTHING else, end of.

The entire Berner breed is inundated with cancer with most of those dogs dying off by age 6-7. The breed is also extremely stupid, I know several of them and there is not a brain cell among them, but, they were not created for brains.

In closing, a dog you can actually rely on for real world protection will cost you over 10K and up to 35K, forget that notion.

Have you tried Googling "dog breed selectors"? Honestly, that might be your best bet. A large breed might not be best if you're going to be in a tiny apartment. You might also not be able to have a large breed, since many landlords have size stipulations on pet dogs. You can always buy several cans of wasp killer spray. Some of them shoot close to 40', so if someone breaks in, you grab the nearest can and spray without getting grabbed.

Look for working dog breeds. They tend not to need all sorts of running around space. That doesn't mean no exercise though.

Maybe a German Shepard or a Boxer. GS's are known for their loyalty but can be mean, Boxers are also known for loyalty but are less known to be mean or aggressive. :)

Any dog as long as you care for it properly, breed/size have no bearing on it.

Australian Shepherd, any herding breed.