Zenith- you can essentially get any e-book reader or tablet today, and it will work for you. It really depends on budget, and if you want additional features like being able to connect wirelessly, have access to the internet, etc.
I have a tablet by Samsung, and you can download apps for the different e-book publishers or download a e-book reader that will read .pdf's as well. Its really useful. Its nice because you can connect to the internet wirelessly, and go to a website like archive.org, and download a TON of free Catholic classics. A friend shared a timeless work by a very popular and holy cardinal; it was a pdf formatted docuмent, which was made by a seminarian by taking a photograph of a 5 volume work. Many many pages, and its extremely rare. These are things you might not have access to otherwise; but I could be wrong.
So my 2¢: Kindles are nice, but I don't know if they give you access to this plethora of hard to find, out of print, impramatured, classic Catholic books and information.