Personally when I was considering what school to attend, I was deciding on what place would make me feel the most at home and happy. I recommend you think about where you can see yourself being happy.
Regarding research. If you want to do it, then you'll be able to find a mentor in KC to help accomplish it. But the question is honestly more about whether or not you will after 10 months of medical school you'll want to spend your 1 month off working and specifically for a project you'll potentially have limited exposure to in terms of finishing. I think when considering that I wouldn't believe KCU to be the most welcoming to doing research your first year summer. That being said, we have so much elective room that it's not difficult to audition and do a ton of research rotations successfully.