I got the original Mac Mini in 2005 because I wanted something that was easy to transport occasionally, but I didn't want a portable to tote around day to day. When the HDD and the power supply failed, I replaced it with the 2009 Mac Mini that I am still using today..... and probably will do so for some time ahead.
As a teacher I occasionally took my Mac Mini to use at work, with an LCD projector, usually for presentations using Keynotes / PowerPoint (If you don't have Microsoft Office installed, Keynote opens PowerPoint, and it works just fine). It was just a few times a term, with minimal hassle. It takes just a couple of minutes to hook up and disconnect the Mac Mini, and it is easy to transport in a back-pack on a bicycle. However, I did, and still do, most of my work outside class at home.
More recently I have been using more computer based material, and found myself needing a computer in class most days, so in the middle of last year I bought a MacBook Air, the 2017 model, which has been fine for my needs. It is still available new, and is the cheapest MacBook available, starting @ $US 999....... That is $200 more than the base model 2018 Mac Mini, and $200 less than the new generation 2018 Air.
So there are you current options available new. If you want to save some money, check out refurbished earlier generations of the MacMini (the 2014 would probably be fine for your needs) or the MacBook Air.