If you exaggerate, all e-books are divided into:
3. With their chips
4. The rest
Sony is good, above all their quality. They have a great design, build quality, a more or less reasonable software, but not support FB2
"The paperback book" and "other" differ generally only software. At least 301. As I understand it, the hardware platform, PB, FReader, and many others — one and the same, and the difference is in the software. Moreover, the quality of the software PB is so much higher than competitors, that is any overpayment.
Well, all sorts of Kindle and Nook — they have the main feature — in service shops.
In General. choose what more you need.
I have the PB301+ is a great device.