What's the best tablet for reading pdfs for me?

I need a dedicated tablet mainly for studying and highlighting 300-page scanned textbook PDFs without constant zooming or eye strain. What screen size and display type should I look for that handles large documents smoothly?

To be fair, anything under 11 inches will make you zoom constantly on full textbook scans. Honestly id look at a 12 or 13 inch screen. A big iPad or an Onyx Boox is perfect if eye strain is your main issue.