Isn't Indiana an enormous school where they split you up into different pre-clinical sites?
If so (since you already mentioned cost is the same), I would go with SLU for the single campus and bigger city aspect. I wouldn't want to get stuck in the middle of nowhere, Indiana, paying OOS fees. Or actually anywhere in Indiana, but that's just me.
Biased toward St. Louis (WashU grad), but also have experience with Indianapolis through family. If you're choosing between satellite campuses in and around Indianapolis vs St. Louis, STL would definitely be a big step up IMO. You'll find a lot of culture, a vibrant community, and a solid college/med school crowd between SLU, WU, and UMSL.They do have a satellite campuses, but you more or less get to choose where you go, especially if you have reasons for wanting to be somewhere like Indianapolis, South Bend, etc. And if your looking for a bigger city aspect... St. Louis is definitely not the way to go... that city is so empty that its not much different than being in Indiana (Indy isn't exactly a small city either, 2 million-ish last time I checked.)