I think if you are 15 right now, instead of thinking about which university you want to go to, you should focus more on what you enjoy doing or spend time figuring out what your passions are! It's important to study what you are interested in rather than choosing a university just by their image or reputation!
Don’t worry about that before you start searching !! I went to uni not knowing what I wanted to study but going into the faculty I’m in now, I realized I enjoy what I study right now so I guess it’s also important to just go with what you feel is best for yourself at the time you apply!