I'm Regolith. I'm a first year Mechanical Engineering student, aviation enthusiast, hobbyist writer, and dedicated Minnion from back in the aRTD days. This is maybe my second time actually posting in the forum, so hey guys!
Welcome, I'm 6 years into a Mechatronic Engineering degree so hopefully you get through it a bit faster than me.
And yeah you can use an engineering degree for anything that involves projects, management or,
surprisingly, project management, so my advice is to try all the different facets. Process engineering, management, validation, project planning and so on, find what you enjoy the most while you're studying so you know what you want to do once you get out.
Noodly, it pretty much depends what you want out of the study. I would recommend Aerospace if what you're planning to do is quite related to it, otherwise Mechanical is a bit more widely applicable. One of my friends I started with in my Mechatronic degree is currently studying part-time while he runs his orbital payload deployment start-up company, so as long as you're passionate, you'll make it work.
However if you want a job at an established aero company (Boeing, Lockheed, Space-X) you will need an Aerospace degree to work directly on their main projects, or so I've heard. They can be... selective in that sense.
I am a little biased because the fluid mechanics equations you use for flow look like this (and I have to do my next Fluid Mechanics subject this upcoming semester), though fortunately a large percentage of the terms drop out for most applications.
(Yes that is a single equation.)