Amazon has a reputation for rock-solid firmware, and B&N Nook has a reputation for being slow.
B&N limits you to 500MB of sideloaded books (including books you download from B&N and transfer via USB) plus 2GB of books downloaded through the device itself, whereas Kindle doesn't care where you get your books from. You can convert your old B&N purchases with
calibre and store them on your Kindle, but not the other way around since the memory is restricted.
B&N is a dead platform. They've always played second (or third) fiddle to Amazon, in terms of popularity
and workmanship in their devices. Consider the fact that they just fired a whole lot of engineers (since they apparently don't need them anymore), see here:
https://www.mobileread.com/forums/sho...d.php?t=233564
I would suggest get anything other than the Nook. If you want EPUB/library ADE support, and the ability to tweak your reading experience, go with the Kobo. If you like Amazon or just want a simple clean reading experience, go with the Kindle.