I have the Libre.
Libre can do DRM epub books so that I can borrow the ebooks available from the public library sites. This is the main reason I bought it over the Jetbook/JBL. I do wish I could get dictionaries, would be helpful in learning a foreign language. I also wish the public libraries had a bigger selection. But so far I have borrowed two books and at least saved the money from buying them.
I have several pdfs on my Libre. With reflow on it reads like an ordinary text file albeit with many line breaks. Without reflow the entire document is formatted like the original and you move from section to section using the arrows. Frankly I prefer without. Never had freezing or had to do a reset with my Libre. And remember if you get Jetbook or Libre (but not JBL) you have an mp3 player, not great, but at least you can take a break from reading on with only one device.