One thing that I really like about OU that they highlight a lot of in the first two years is the Module system where you are assigned a mod with about 14 to 15 other classmates where you each have your own desk, discussion room, lockers, small kitchenette, etc. and basically these people will be right with you for the next two years. While the mod system is sort of what you make of it, my mod is very close and includes some of my best friends that I may not have otherwise met beyond my friends not in my mod. In a way they almost give you a group of people to trauma bond with while also serving as your partners for a lot of group clinical work. Obviously its sort of luck of the draw but something that I have loved.
I also really like how much OU prioritizes early exposure to different fields, there is always at least three interest groups for different subspecialties going on, and with each of those there are workshops and doctors that come in and talk about what you can do to pursue that field. Faculty are very accessible and care about your grades, and while they acknowledge it is hard, they also will work with you and help you improve rather than let you flounder like a lot of other schools and will help you put together things that you my be missing in your skills that can take you above and beyond. (I wouldn't say this one is as unique but a positive so far with my time here.)
Edit: As well attendings are directly involved in our clinical and lecture courses, all the way up to the chiefs and administrators of each department and even they make themselves accessible to be discuss with you course of actions in pursuing a specialty and taking a first-hand role in our teaching. It can be scary trying to interact with attendings and residents in the field when we are medical students but OU gives you a lot of opportunities (if you take them) to make connections with doctors that can have a tremendous impact in mentorship and teaching. Again, something that you have to sort of grab by the horns but I've heard may not be the same at all schools.