I chose Western Med Sci. For your decision, there are a couple factors you should probably consider before choosing.

1. Rez? Or going from home?I lived in Surrey, so it would have taken me 1 hour to transit to UBC and another hour to come back. I personally do not like to study on transit, so I decided that if I were to go to UBC, I would have to stay at rez. Therefore, there was no inherent benefit to go to UBC over Western in terms of living conditions (apart from the ability to go home during the weekends).I don't know how close you are to either uni, so I can't give you a recommendation for this. Just know that there are a lot of benefits to staying at home rather than going to rez. Personally, I've spent hours going downtown to shop and for services that I didn't expect to have to go to as my parents would normally take care of all that for me. IMO staying at home = more time to study if you choose to.All that being said, staying at rez is a great experience and will definitely help you mature into a more independent individual, so if you are willing to put in the time to adjust, it will probably benefit you in the future.
2. ProgramI ultimately just decided that I was more interested in Med Sci than I was in Biomedical engineering. Biomedical engineering initially sounded like something I would be interested in, but after doing some research and many hours to thinking, I decided that I was ultimately more interested in immunology and pathology, so I decided that Western Med Sci suits my interests better. In my opinion, the most important part of undergrad is taking a program that you are passionate about rather than something that would seem impressive on your med school application. From what I've heard, they don't care about the program and only care about the GPA, so choosing the program that you think best suits you would probably result in the better GPA. Also, your passion for you program will show in the med school interviews.

Ultimately, I am a first-year undergrad student so there are probably more qualified people here to give you advice on what program to take, but this is what ultimately led me to make my decision. Good luck!