More user friendly and I believe its a more trusted program.
References :

I recommend you this article, which is written by a person who has tried a number of ebook readers, including the Kindle and Sony. It is also the best review I’ve ever read about ebook readers:

http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2Freview%2FR3QM7LGL62MZ4X%3Fie%3DUTF8%26ref%255F%3Dcm%255Fcr%255Frdp%255Fperm&tag=ereader-2-20&linkCode=ur2&camp=1789&creative=390957
References :

http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2Freview%2FR6L0G6ZY33S96%3Fie%3DUTF8%26ref_%3Dcm%255Fcr%255Frdp%255Fperm&tag=more_info-20&linkCode=ur2&camp=1789&creative=390957

I suggest you to choose the Amazon Kindle. It is selling better than the Sony Reader, and the Kindle is now having the biggest share in the ebook reader market. It has free internet access and reading aloud functions, which is not available on the Sony Reader.

Hope this helps.
References :

The Kindle doesn’t read Word natively; it has to be converted. This can be done through Amazon’s service (free if you get it through email & download it yourself; costs $.15/mb if you have it sent wirelessly), or through Mobipocket.com’s free conversion program.

The Sony series read RTF natively, and will convert RTF and Word to formats they use.
The Nook has given very little details about what filetypes it supports natively; nobody’s sure yet.
The Aztak series read RTF and Word Docs natively, no conversion needed.

Most of the ebook readers come with software that will convert several common filetypes into whatever format they work best with.
References :
Mobileread’s "Which One Should I Buy?" forum: http://www.mobileread.com/forums/forumdisplay.php?f=123

http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2Fgp%2Fhelp%2Fcustomer%2Fdisplay.html%3Fie%3DUTF8%26nodeId%3D200375630&tag=moreinfo-po-20&linkCode=ur2&camp=1789&creative=390957

I’ve the Kindle 2 and I like it very much. I recommend it over the Sony Reader, because buying books on the Kindle is quite a lot cheaper than buying books on Sony Reader. And I know quite a lot of Sony Reader users complain that it is difficult to find book for the device. Amazon do much better in this area, and they provide very good content for its device.

I remember I read these reviews when I decided to get my Kindle:

http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2Freview%2FR2DUM7S4XW06QN%3Fie%3DUTF8%26ASIN%3DB00154JDAI%26nodeID%3D%26ref%255F%3Dcm%255Fcr%255Fpr%255Fcmt&tag=moreinfo-po-20&linkCode=ur2&camp=1789&creative=390957

http://www.speedreaderxreview.com/kindle-2-0-vs-sony-reader-prs-700bc-comparison

Finally, Amazon has just put a price slash on the Kindle 2, and it is now selling $100 cheaper than the price I got my Kindle, and it adds in international wireless access… So take the chance if you want it.

Hope it helps
References :
http://www.amazon.com/gp/product/B0015T963C?ie=UTF8&tag=moreinfo-po-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B0015T963C (Kindle 2 after price slash)

If you are trying to decide between the Kindle and the Nook, I would check this blog (in sources). I bought a Kindle at the beginning of summer this year, and was concerned that I’d made the wrong decision when I heard about the Nook. This article helped calm my worries.

I must admit that I am, as a Kindle owner, a little bias to Amazon. However, I will say that the Nook looks pretty cool. I agree that if you decide to get it, though, you should wait until at least a second edition, so that some of the kinks will be worked out. I’m not too sure about the Sony, mostly because Sony isn’t actually a book seller. In the end, it’s your decision.
References :
http://ptech.allthingsd.com/20091209/nook-e-reader-has-potential-but-needs-work/

Actually there are quite a lot of places where you can find free ebooks for the Amazon Kindle. Some examples are here (some are available on the Amazon Kindle store as well):

http://manybooks.net/

http://gutenberg.org/

http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2Fs%3Fie%3DUTF8%26node%3D154606011%26redirect%3Dtrue%26p%255F36%3D0-0&tag=ereader-2-20&linkCode=ur2&camp=1789&creative=390957

I’ve compared the Nook and the Kindle, so let me tell you my findings. From the official page of B&N, here is how the Nook compares with the Kindle:

http://www.barnesandnoble.com/nook/compare/

Since Barnes and Noble page is only mentioning the advantage of the Nook over the Kindle, let me try to tell more about the benefit of the Kindle 2 over the Nook:

- There is no internet browser for the Nook. So even with Wi-Fi, you can only use it to purchase book. You cannot do searching in Google, Wikipedia, check email, etc., like what you can do with the Kindle.

- The Amazon Kindle has international free 3G wireless which covers over 100 countries. So even if you’re in places like the UK or Australia, you can access the internet with the Kindle free of charge. The Nook has wireless only within the U.S., and is limited for use of buying books only

- The Kindle is available outside the U.S. (it ships to 176 countries), while the Nook only ship within the U.S. at this moment.

- The Kindle has text-to-speech function, so it can treat an ebook like audio book. This function is not present on the Nook.

- The price of ebooks for the Nook on Barnes and Nobles are more expensive than the ebooks on the Kindle. This can make quite a difference in long term, the price difference adds up as you buy more books.

- Amazon is already doing some change after the Nook is announced (still more than one month for it to be available). They dropped the price of their International Kindle even further. And they are going to release a PC software which can read their Kindle books. They also added native PDF support for their Kindle 2.

One more thing to be aware is that, at first glance you may think the Nook can read ebooks with color touch screen. But indeed the color touch screen is only a small screen beneath the greyscale eink screen, and seems it is only used to browse the cover of ebooks.

In my opinion, it is a tie between the Kindle and the Barnes and Noble. But if you may travel and you enjoy reading during your trip, you should go for the Kindle for sure. Moreover, I trust the Kindle will come up with some strategies very soon, like improving their lending book function. The Kindle is the biggest player in the ereader market right now, and I believe it will put enormous effort to hold its position. Finally, if you’re an avid reader, price of ebooks will also be a big concern, as ebooks on the Nook are more expensive.

I recommend this article as well, it is the best review on ebook readers I’ve ever read:

http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2Freview%2FR3QM7LGL62MZ4X%3Fie%3DUTF8%26ref%255F%3Dcm%255Fcr%255Frdp%255Fperm&tag=ereader-2-20&linkCode=ur2&camp=1789&creative=390957

Just check up their homepage to see the latest price of the devices. The price is most up-to-date, and if there is any price change it will be reflected immediately on their homepage. BTW, the Nook seems to be in stock only in Jan 2010, so you’ll not be able to get it in X’mas…

Hope this helps you decide.
References :
http://www.amazon.com/gp/product/B0015T963C?ie=UTF8&tag=ereader-2-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B0015T963C (Amazon Kindle homepage)
http://www.barnesandnoble.com/nook/index.asp?r=1&cm_mmc=Non-Member-_-Merch-_-091020_NF01_Device1-_-na (Barnes and Nobles Nook homepage)

I like to use the text-to-speech function on the Kindle too, meaning that I can "read" with my hands and eyes free…

And I remember I read these reviews when I decided to get my Kindle:

http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2Freview%2FR2DUM7S4XW06QN%3Fie%3DUTF8%26ASIN%3DB00154JDAI%26nodeID%3D%26ref%255F%3Dcm%255Fcr%255Fpr%255Fcmt&tag=moreinfo-po-20&linkCode=ur2&camp=1789&creative=390957

http://www.speedreaderxreview.com/kindle-2-0-vs-sony-reader-prs-700bc-comparison

Hope it helps
References :

The biggest thing for me was prices. Sony’s books are consistently more expensive than the Nooks which are consistently more expensive than the Kindles. The Kindle also has the highest number of books available in current reading (like the NYT best sellers). Gimmicks like the touch screen or LCD screen on the Nook just seem to slow e-readers down at this point. Maybe one day in the future they’ll work efficiently, but until then I won’t be buying an e-reader with one.
References :