Disclosures: I turned down my SLU offer in favor of another school, and I don't know anything about MCW. But I know what you're going through and I hope this insight is helpful! Also, I'm from STL.
SLU is in STL, which has the feels of a small town with the luxuries of a city. Big beer scene, big sports scene, but there is also a lot of art/music to be found. Really nice parks including tower grove and forest park, which has free museums and is wonderful. Some really good restaurants.
True P/F for the first two years which is nice, but the larger class size (~178) is something to consider. The students sounded generally pretty happy. SLU also cares a lot about community service so there are a lot of opportunities for that if you are interested. The new hospital building seemed really nice, and the campus is really pleasant. The administration sounds like it really genuinely cares about student wellness and has lots of support. One of the students said 'it is really hard to fail here' lol which I took as a positive!
At my interview, I asked the students about research/mentorship opportunities and one of them was like 'ok im gonna level with you'. He said that research was really hard to come by, and in his opinion professors seemed spread a little thin and mentorship was a little lacking. Not sure if that was just his experience but it gave me pause. A few years ago, a lot of the faculty jumped ship because of payment issues and some (def not all) of the programs had to basically rebuild from scratch, may relate to the mentorship issue and may get better as the new faculty settles in. The facilities are also definitely a bit dated, aside from the new hospital building.
Re: the religious affiliation. I had the same worries as you- I talked to a friend and current student and they said that while mostly it didn't come into play, they did feel the presence on service for obgyn. Coudn't really go into details when I pressed, didn't seem like it was anything outrageous but a definite religious influence.
SLU overall has a really good reputation in STL. Students seem really happy and the program really cares about its students. It's just deciding if it's the right fit!
Feel free to ask questions- like I said I'm from STL and learned quite a bit about the program so happy to help as much as I can! Best of luck- this is a great problem to have