eBook Devices? Which one to get?

My 11-year-old niece is an voracious reader (putting it mildly). She is never without a book (and not just one), and she reads her favorites over and over. She would like to get an eBook reader for Christmas, and didn't know which one to ask for: Kindle, Sony, Nook, Pandigital, Augen, Literati, iPad? There are many to choose from.

What features are important in a eReader? 
I recommended that she investigate an eReader that also includes a desktop app, such as Kindle or Nook, since she already has a netbook that she travels with (and uses mostly to play games -- mom regulates Internet access on the device). And for the more "generic" readers, Adobe's "Digital Editions Software" provides a way to read eBooks on PCs and Macs. This way she can begin reading eBooks on her computer and determine whether she enjoys reading from a computer screen vs. a paper copy. She is also looking forward to the portability and space-saving features of electronic text.

connected – adaptable – flexible – customized

This white paper from Adobe, addresses the issues of authoring and delivering eBooks across devices:  http://www.adobe.com/products/digitaleditions/pdfs/adobe_ebook_platform_whitepaper.pdf. The authors state, "it’s becoming clear that eBook readers want:

• An open environment where readers can download books from a variety of sources
• Interoperability among devices
• Ability to share books with friends"

This weekend we downloaded the Nook desktop app and located some free eBooks from Project Gutenberg -- ("the place where you can download over 33,000 free ebooks to read on your PC, iPad, Kindle, Sony Reader, iPhone, Android or other portable device."). We also discovered (through the Adobe white paper, that "The nook user can download books from the public library via the Overdrive Content Reserve system. These books expire after a certain period and are returned to the library." If you are looking for additional places to download eBooks, check out http://www.freeliterature.org/

As we were researching, we discovered this website, http://www.the-ebook-reader.com/ which states is an "informative resource for everything about the growing world of electronic book readers, often called ebook readers or ereaders." We found reviews of a variety of handheld devices, links to holiday sales and more.

Can you help an 11-year-old decide? Which is your favorite eReader device and why?