I don't know much about Liverpool and I know Exeter is a good uni but I've heard some questionable things. I'm most likely going to choose Reading because I quite like the course content, campus is clean and good plus very close train links to London. Moreover, I believe you do get placement opportunities firmed to you - you can choose a more clinical or 'sciency' route such as in labs. The best thing is that the Royal Berkshire Hospital is close and they have links with them; I believe that would be great for GEM. I went on the Open Day and it's honestly quite nice, town isn't bad either as lots of major shops/restaurants (as someone who actually resides there). Hopefully this helps! Liverpool, again, I don't know much about it but I know it is a Russel Group. However, prestige doesn't matter at all for Med! Reading is also ranked consistently highly in degrees such as pharmacy so I feel like it will defo move further up.
Hopefully this helps in terms of UOR!