Typically I use pen and paper, but I've been interested in a tablet or similar device for a while and am interested in what other people are using.
The reMarkable 2 seems like a really cool option to play with, but also pretty pricey for trying it out to see if it would even work well.
While it's not directly related, when playing in games, I usually use a paper character sheet for reference, a notepad for consumables, story notes, and HP, and Pathbuilder on my phone for spells.
I've become so fond of Foundry's set of tools that I think at this point I'd prefer it over face to face. It just handles so many things.
If I ever do get into a face to face gaming situation again, I might look to see if I could have a set of tools on par with what it offers for handling dice, action order, telling me if something can be done or not, correcting me on my encounter building (too high or too low CR for example), and other tools.
That seems to be an issue with older PF2E modules.