Remarkable

Don't know anything about Zotero but if you can print to PDF on your computer, you can read and annotate it on the rM2. There are also browser extensions available that might help.

I've never written on an iPad but I have on a Surface tablet and I would recommend the rM2 easily over that experience. That was with a $100 Microsoft Pen too... The rM2 actually lives up to its promise of feeling like paper. It's not just the textured screen, it's that plus the response time and intelligent design.

I opted out of the competitors because I wanted a device that I wouldn't have to think about. I wanted a device I could set next to my laptop for 8-10 hours per day and just be ready for me to jot down, take notes, sketch a chart, etc., etc. and be able to easily recall those notes at any time. I got what I needed to the letter, and it works great for all that and so much more I won't go into as this is getting long already. I highly recommend if you are serious about wanting a good writing focus tool.