When reading for entertainment, I like e-ink. It's so much easier on the eyes. If you really get into a good novel, you can read for hours without the strain you get from regular tablets or a computer screen. Also, the Kindle is so much thinner and lighter than a paperback.
Something else I love about the kindle is the vast library of free books you can get. I figure I've saved hundreds (maybe thousands) of dollars over the years with the free books. Mostly classics and unknown authors. Just because they're unknowns doesn't mean their stories are bad. A lot are very very good. If I hadn't found them for free, I never would have read them and got the enjoyment from those stories.
I think a lot of it comes down to what you want to read. If it's technical manuals with lot's of pictures, or magazines, anything with a lot of visual aids, you're probably better off with a full featured tablet. If you just enjoy reading for fun, and most of those are novels with zero pictures, then you can't beat e-ink tablets (IMHO).
Last, the Kindle's battery lasts forever. I think I charge mine once every two or three weeks.