What major should I apply to as a first-year University of Michigan student to have the best chances of getting in?

Apply with the major you're interested or something that you can switch back to your first choice easily because what's the point of getting accepted into UMich if you can't study what you want.

Well, I think you can get a slight statistical edge by applying to a less popular major. Be aware of the fact that this is a commonly-known "loophole", so many people will probably have the same thought as you, and also apply to a less popular major with intentions of switching to a more popular one.

If you can find an obscure popular major that your co-curricular portfolio and your academics fit really well to, that'd be amazing. I would go for the obscure popular major then, because colleges do want classes with diverse interests/future plans. However, if you pick a major that the rest of your application doesn't fit to at all, I'd reckon you'll be at least somewhat penalized for it – in the sense that it takes away some coherency from your application, and obscures what your actual personality. In that case, I would just apply with the popular major.

So it honestly depends whether you can find an obscure major that you can convincingly pretend to be interested in :D No worries about switching later down the road; as long as you're not applying to some sort a restrictive program, or the university you're applying to is subdivided into schools, switching majors at American colleges is often as easy as logging into the school portal and clicking on a new major.