If you go with a large screen, Onyx is definitely the most tested device. It runs Android so you can install PDF reader apps, and it comes with its own software. I suggest you read about it in the Onyx sub-forum.
The only other reliable alternative is the big Sony PDF reader, but that will be hard to find at the moment, and they are releasing a new one soon.
Using a smaller device is possible, but difficult. If you try to use a small device, I suggest you look at kpdfopt
http://www.willus.com/k2pdfopt/
https://www.mobileread.com/forums/sh...d.php?t=144711
This will reformat a PDF to fit a 6" screen.