I just upgraded my sony reader touch to a sony reader touch with wifi :) I can't wait to get to actually play with it :) I personally chose the sony over the kindles or nooks for a few very specific reasons.
1. I don't like being told where I HAVE to buy books. Kindle and Nook are more limited than the sony.
2. Authors can SIGN my books directly on my Sony :) Don't have to dowload an "app" for that to happen.
3. EXPANDABLE MEMORY. I can have up to 32 gigs of EXTRA memory, on top of what's built into the reader.
4. More formats. Sony reads everything BUT Kindle and Nook formats.
5. It came in red LOL ok this wasn't a HUGE factor in my decision but it did finish tipping the scales LOL
So that's what I have.
Hubby on the other hand got suckered into the Kindle craze. He had the kindle keyboard (without the ads) but we sold that to my mom and he's getting a kindle fire for the holidays.
I personally wouldn't go with something that restricts where I can buy, charges me if I buy a book from elsewhere to convert the file, or limits me in any other way. I'm probably one of the few people on this planet who doesn't and WON'T own an apple product (the proprietary nature of their products just being one of the reasons ... Steve Jobs' bullying is another).
Check out all the e-readers out there, (theres WAY more than just the kindle, nook or sony) decide what features you NEED, which features you WANT and what exactly you're going to use it for. Those are the most important. Then you can look at things like styling, color, available accessories, etc. After that go with whichever one fits your budget best and enjoy.
I haven't met anyone who doesn't LOVE whichever e-reader they have.