I liked my 13” pro for school and have had it for ten years, easy to fit on desks and still have space for a notebook, also if you every plan to use it on flights the 15 is big enough to be pretty awkward.

I don’t use my 13 with monitors very much, so I’m looking at sizing up to a 16” this year. If you plan on primarily having it connected to monitors then a bigger screen on the laptop itself probably won’t matter to you.