I'm a third year at NYU. With regard to Loma, I only have rumors from faculty at my school. The general consensus that I've heard is that Loma has a much more humane atmosphere after some 20 years of deliberate effort and maintains a "highly curated" class composition. My best guess is that after the formal stuff, accepted students fall within a certain range of culture and temperament profile.
In terms of culture at NYU, I can say that like anywhere, it is a mixed bag because you cannot get along with everyone in every context and relationships change. Realistically, most people who come here aren't looking to specialize. They are mostly looking to graduate as painlessly as possible and get to work. In part, it is because NYU does skew a bit older with a chunk of married people and some with one or more children who may prioritize other things over getting top grades. Some have side hustles. Most people have something going on and I think for that reason, it is not as competitive as one might expect of a class of ~390.
For those who want to specialize or need an outlet, there are so many opportunities beyond traditional research, student club leadership roles, or shadowing. Plus, selection for prestigious opportunities is pretty fair. As an example, you may take only 1 honors elective as a D4 and there are more than 10 of those. You don't see the same few students doing all of the most selective things.
Like getting into dental school in the first place, it depends on how you are going about your life. As long as you meet the invisible, shifting, and relatively arbitrary minimum, someone will take you where you want to go.
Go for the lifestyle you prefer and everything else will fall into place.