Years ago, I personally made the decision that I wanted a reader, and not a tablet computer. For a reader, I have a Kindle touch and I love it. If you are looking for a reader to use by the pool, e-ink - whether Kindle, Nook, Kobo etc are wonderful. They are light, easily portable, have great battery life. However, they are Not tablets - they are not for sufing the net, or doing basic computing. If you want something to use as a tablet, then you will have to decide among the plethora of tablets that are out there. However, most tablets are not good for reading in full sun.
Happy sailing!