If you want epub support (the industry standard), nook touch is the way to go. I love my nook but have nothing against kindle other than its lack of epub support. Nook Simple Touch is also $80.
Both are almost identical in terms of usability and readability.
Both come with firmware that tries to bind you into a specific ecosystem. Both are a bit obnoxous with their intrusion into your reading habits.
Amazon (Kindle) has better customer service if that is important to you.
Nook has physical presence (B&N bookstores) which I find attractive.
PCMag does a fair comparison of the two devices.
http://www.pcmag.com/article2/0,2817,2372819,00.asp
There are many other devices also, but I don't know much about them.