I will generally agree with the rest. If you're looking for the best READING experience, an e-ink based device is the way to go. You get very near print quality, but at the expense of things like refresh rate. E-ink readers are very specialized for reading. Among the various e-ink devices, I'm preferable to the Kindle, and I've looked at quite a few. The Nook has some odd partitioning of the internal memory, with a good chunk of it being reserved for stuff you buy from B&N. You can root them and rearrange that, but not everyone wants to do that. You also have about half the internal storage on anything other than the Kindle.
As for Kindle Touch vs non-Touch... Kind of a tossup for me. The touch will be a significantly better experience if you're the sort who likes to annotate books, but then the non-touch has the handy hardware page turn buttons. Then again, the touch will suffer from fingerprints and other problems that plague touch screen devices.
If you want to do anything other than reading, then a tablet would be the way to go.
Either way, you can use the free program Calibre to convert between formats. PDFs are generally the single worst format there is to convert from, since it's closer to an image format than a text document, but as long as there are no headers or footers you can usually get an acceptable result.