I like bringing it with me when travelling, to watch movies on the plane. More portable than my laptop with a bigger screen than my phone.

i sometimes use one for certain tasks, where a big screen device is needed, but i don't want to haul around my big laptop.

The only tablet I can recommend is any iPad with pen support. It has been a lifesaver in my uni life, by taking notes digitally I saved dozens of notebooks and otherwise wasted paper, plus the convenience of having my digital books that can be taken everywhere saved my back. I think that for a university student the base 128gb (or even a 64gb one) iPad and a knockoff apple pen for 20~30€ is a worthwhile investment.

They're useful if you have kids, otherwise I haven't found them really useful.

I can see it a whole lot better in bed, or around the house. The phone is too small. I only use the phone outside of the house when I'm mobile, except for hotels, then I'll use the tablet.

My wife got me one years ago, and I'm using it as a dedicated YouTube player when I'm doing something around the house

I think they would be far more useful if all of them had pens.