I prefer the Kindle. I use mine daily while commuting to work. Easy to carry and fit into my bag. Plus, when I turn it on, I am ready to go... right where I left off. No issue with a bookmark falling out and such.
Another positive aspect of the Kindle is privacy when reading in public. Believe it or not, pulling out the latest book on Witchcraft or Wicca and reading it publicly is not always a wise choice. The cover will draw attention, many times good, sometimes bad. With the Kindle, no one knows what I am reading.
We have 100's of books in the home, however, as my wife prefers books to the Kindle. :) We have a "balance" so to speak. :)