I loved each of my Kindles, that is why I kept on getting new ones. Kindle PaperWhite is the best to date.
OK, let’s be a bit more objective…
If you are sticking to the “dead tree” form of books, no problem. EBooks are not guaranteed for centuries, or even decades. You cannot write or dribble on them. There is no “pop-up” version of eBooks. It is difficult, sometimes impossible to lend or borrow eBooks.
Under certain situations, however, eBooks are near ideal. You can “carry” many eBooks and give no thought to their physical weight. When you check out an eBook from the library, you don’t worry about losing it, or forgetting to return it. It is arguably greener and the books are frequently cheaper, sometime even free.
Other than the cover, the vast majority of the books I read are monochromatic. For my aging eyes, I need good light to read. I don’t read continuously for more than a couple of hours per sitting. My favorite reading position is a reclining against a pop-up pillow in bed, with one handing holding the book. For me, Kindle PaperWhite is ideal.
IPad mini will be a very good choice, except for the price. People rarely use it solely as a eReader, but more as a general purpose tablet. As an eReader, its colors make magazines much better, particularly those emphasizing photos, such as National Geography. The biggest issue I have with iPad mini is really the price. If you must choose one and the price is not an issue, get an iPad mini. If you are an avid reader and are cost conscious, go for Kindle. Many that I know have both and don’t think a choice among them is necessary.