I used an iPad mini for a short time when it was first released. I loved it, but eventually fell for the siren song of bigger-better-faster so I upgraded and upgraded and upgraded and ended up with the giant 12.9" iPad Pro with Smart Keyboard and Pencil 2.
The big iPad Pro can (and does) easily serve as a primary computer for many people. I've learned that it'll never fill that role for me. A "real" Mac is where I prefer to do most things.
What this means is that I can never decide whether to carry my MBP or the big iPad so I end up dragging them both along. This rarely makes sense.
What I now have is a 2019 iPad Mini and after a very short time I can tell it was the right move. I don't have to decide which to bring. I can easily bring both with almost no additional overhead.
"But the big iPhones are practically the same thing," you may argue, but you'd be wrong. Hold them up side-by-side while viewing just about any document or book or image and if you think they're "practically the same" you're kidding yourself. The iPad's aspect ratio is also much better for viewing the things I want to look at.
It works with the (1st Gen) Apple Pencil, which is awesome. I mean that using the Pencil with the Mini is awesome. The 1st-Gen Pencil is an ergonomic embarrassment, but still.
It's nice that I can actually thumb-type with the Mini, too.
The new iPad mini is fast, small, has good battery life, and takes up almost no extra room. I think it's the iPad for me. Maybe it always has been.