I'm in a small combined degree program (~50 people) within a larger med school class (~200). While there is plenty of overlap between our classes, we also function independently in many ways, so I feel like I get a taste of both experiences.
Socially, a lot is going to depend on your personal preferences - I'm very happy being in the smaller program, because I tend to thrive in these kind of settings, and like the camaraderie that comes along with a smaller, tight knit program. However, I have friends in the larger program who prefer the freedom of the big class - more people to make friends with, not everyone knows everyone else's business/has to see each other all the time.
For lectures, it probably depends if they are mandatory or not. I like being in small classrooms with only a few dozen people - but you can get that from a small class size with mandatory lectures, or a large class size with non-mandatory lectures (since much of the class is probably watching from home). small class size + nonmandatory lectures = even smaller classroom! I don't think I would have done well in a large class with mandatory lectures, but maybe that's some peoples jam.
For research/resources, it will depend a lot on the context of the school. A small medical program within a large research university may have more opportunities for research, etc than a large class size within a smaller/less research focused institution. A larger class size may mean more faculty, or it may mean more competition for access to the same number of faculty. A small class size may (or may not) get more face time with their faculty. I don't think you can judge this off of class size alone - you would need to know more about the school itself.