I have a Sony Reader (the old, old PRS-500), but I love it dearly. Do not buy the new Sony Reader Touch. Apparently, the “touch” tech gives the screen a glare that makes reading difficult, and that’s the entire purpose of the device, right? Forget the Touch and get a regular Sony Reader if you’re going Sony.
The Kindle is nice and and all, but I still kinda don’t trust Amazon after that remote-deleting of 1984 debacle. Plus, it seems to me that the hardware keyboard takes up a lot of space on the device and doesn’t have much use.
The Nook is my current favorite ereading device and the one I recommend to people looking to get a device. I haven’t played with one myself, but I like that the LCD screen can serve multiple purposes, like browsing books AND as a software keyboard. It’s easier to navigate on a Nook because the LCD screen has a better refresh rate than the E-INK screen (the Kindle makes you navigate through the E-INK screen and I imagine it would be slow and annoying). Best of all, it’s running Android, which means the software behind the little screen can be updated wirelessly and people will write apps for it. Think about all the possibilities: a dictionary app to look up words (which I think is already included, btw), an app that fetches the Wikipedia information about the book or author you’re reading, an app that connects to your LibraryThing account, etc. The only drawback I can think of is that the LCD screen might drain your battery slightly faster, but B&N still claim a battery life of around 10 days.
If you don’t need the wireless capabilities or the fancy LCD screen, I’d suggest going for a Sony Reader (non-touch screen). I personally have an extremely large ebook collection on my computer, literally enough for several lifetimes, so buying an ebook over the wireless would be a very rare occasion for me. For the less tech savvy, those without ebook collections or those who’d enjoy the extra features offered by an LCD screen (like word search, annotations and notes, etc.), the Nook appears to be an excellent choice. If I had the money, I’d probably go with the Nook anyway just to see what developers come up with for the extra screen.