I've owed two eink readers. The first was the original Nook. I chose it because I could borrow library books. Time passes and my daughter gets a Kindle PW1. I loved the light! Then, my libraries start loaning in Kindle format. Next think I know, I am reading on a PW1!

I gave my original Nook away and it's still being well used and loved.
I have only had one tablet, a Samsung Galaxy Tab 7.0 Plus. I see no advantage to a Fire unless you want to watch Prime videos on it. Otherwise, from all I have read, an unrestricted Android tablet is a better fit for me.