I do not know anything about aviation. However, on the basis that you might not get many (or any) responses, I thought I would at least say what I know about the schools.
We visited Mount Allison a few times when both daughters applied and both were accepted. It is a very good small university. It is usually ranked as the overall #1 small “primarily undergraduate” university in Canada. It is not necessarily the best for any particular major but overall it is a very good school. It is in a quiet small town, but is not too far from Moncton which is a pleasant small city. We liked it quite a bit. We stayed in Moncton for most of our visits.
We did not apply to or visit the other schools that you mentioned. Waterloo is of course famous for computer science. I have however heard that it is quite good for a number of other programs (for example including music).