Alright, by popular demand, I'm gonna de-anonymize the schools: the choice is between Columbia (Ivy) and Johns Hopkins (Great School). Whereas it seems like Columbia has a better overall CS reputation, Hopkins has a better NLP reputation, especially in machine translation research. I think I'd be happy doing NLP research at either, but my research fit is better at Hopkins.
However, Baltimore is definitely not my favorite place due to its smaller size, lower-quality public transit system, relative lack of cultural/social opportunities, and worse overall cultural fit for me. (And to address @rising_star, it is quite dangerous, especially the northern parts of Charles Village. I got cornered and mugged at gunpoint within my first hour there during a summer internship at Hopkins despite paying attention to my surroundings). Meanwhile, New York is my dream city, and I think Columbia's campus is much nicer, if smaller. I don't mind paying a fortune for a shoebox if the location is great, but the funding is more...precarious at Columbia, despite my fellowship. It is also difficult to get anyone at Columbia to respond to my emails stating my concerns; they said I'd be covered for 3 years, but that the latter 2 will depend on my advisor securing grants. I wanted to clarify what the precise conditions of this were so I could make an informed decision, but no one will respond to me. Hopkins has explicitly guaranteed full tuition coverage and a stipend, even after my fellowship has expired; they also always respond to me within the hour.
I agree with juilletmercredi in that location will make a big difference; this is, after all, 5 years of my life. I don't want to hate it in Baltimore. However, NY is definitely expensive, and I could easily visit on weekends with the money I save by going to Hopkins. I could also live in DC and commute to Hopkins, but the apartments in DC near the MARC train station are pricey.
Thank y'all for the input thus far! It is much appreciated.