I had a consulting assignment in NYC from 2013 to 2015 and I was adjusting to my first hearing aids at the same time. Fortunately, many people there talk louder than in other parts of the country. Not sure if this is due to the background noise or just a cultural thing. This helps in a one-on-one conversation, but crowded restaurants, bars, etc. are practically impossible even with premium hearing aids. Everyone is having trouble hearing so they all talk louder! The noise in the subway is just one of the undesirable aspects of this unavoidable mode of travel.
If you can support yourself in other locations, it is certainly worth a try. However, all big cities are going to have some level of noise so a small city or town may be a better option.