I still have my Kindle Fire HD 7", and still use it for reading ebooks, documents, and occasionally playing Sims Free play.
Next upgrade, I will stick to a Kindle for reading ebooks and documents, as my Fire HD doesn't have great battery time - always been like that; have to charge it everyday, and depletes when switched off also.
Maybe I'll go with the Paperwork - pretty sure that's the one I decided on, as I really want to be able to read outdoors (when it's rarely sunny) and have adjustable brightness for night reading.