The Sony Reader is the eReader I own. It also uses E Ink technology (at least in some models) so it offers very good readability of the text and also long and happy battery life (on my model, batter is supposed to work for 2 weeks without recharging). The first model they shipped was released 2006, so they have long tradition in the field and good customers support. Currently they offer 7 models with or without touch screens on different prices some of which compete with Kindle.
Books can be purchansed from Sony eBook Library store (currently US and Canada only).
Compatibility with Adobe digital rights management (DRM) protected PDF and ePub files allows Sony Reader owners to borrow ebooks from lending libraries in many countries (for up to 6 devices!, one of which a computer).
Drawback: no Wi-Fi (or 3G), no support on Linux and no support of Cyrillic letters/books. Good sides, you don’t need Wi-Fi to download book (you do it trough the computer), there is a program called Calibre which do the magic for Linux and also, you can read Cyrillic books with slight modification of the books themselves trough Calibre – I did it, it works beautifully! One thing more is that the don’t have Voice readers.
Also good side is the Sony brand and its intuitive menus. You don’t even need a manual, it’s THAT simple.
What I aslo like a lot is the RSS option – you can download news to your computer (trough Calibre for Linux) and then to put them on your Reader to read them whenever you have time. On next synchronization the old news are replaced with new. Also, you have a lot of models from which to choose – each suiting different needs. And of course, my PRS-600 is so so light. Only 286g.
Also, there are some alternative firmwares who support different languages. If you manage to put your hands on one of those, of course.
Finally, I must say that Sony Readers are extremely beautiful, especially the Touch edition. They have clean lines and only few small buttons. Nothing excessive. I really enjoy this option, because Kindle keybord annoys me big time. Sony Readers are pure and sexy. And very functional.