The number of high-quality e-readers available is mushrooming. We tested seven and gave our highest marks to one that might surprise you.

If you think the universe of e-book readers begins with the Kindle 2 and ends with the Kindle DX, think again. That universe is expanding rapidly. We recently completed thorough hands-on testing of seven of the top e-readers available today and came to a surprising conclusion: Our number one choice isn't from Amazon at all; it's the Sony Reader Touch Edition.
Sony's $300 reader matches the Kindle 2's screen size and quality but adds a touchscreen and support for free e-books and Adobe ePub, an e-book file format that book publishers and resellers have widely embraced. Whereas Adobe's PDF reproduces a fixed image of a page, ePub permits text to reflow in order to accommodate different fonts and font sizes.Certainly the wireless connectivity in Amazon's Kindle models makes buying new books a breeze, but to this point Amazon's readers support only Amazon's format, locking you into buying exclusively from the online giant.
Of course, no company's lead in the rapidly evolving e-reader market is safe. Barnes & Noble looks to be one of Amazon's chief competitors. The giant bookseller announced its Nook e-reader last month, and most people who got a peek at the device seemed to love it. The Nook isn't yet available for thorough testing, however.
E-books have numerous benefits. Eliminating paper saves resources. E-book readers take up little room in travelers' backpacks and purses, and yet can store the equivalent of a whole bookshelf. You don't have to go anywhere to buy or borrow an e-book title. For the vision-impaired, the ability to adjust font size can mean the difference between being able to read a book and having to hope that the publisher will eventually release an audio version. Some e-book readers double as music players, and some even have a speech capability for reading books aloud.
Unfortunately, the world of e-books is Balkanized, with multiple incompatible file formats and digital rights management (DRM) technologies, and devices with varying support for both. Books in the public domain are widely available in PDF and other standard formats. But copyrighted material is another story. Amazon's current Kindles can obtain commercial e-books in Amazon's AZW file format via wireless download only in the United States (in early October, however, the company announced a Kindle capable of downloading content in most countries).

Adobe offers a DRM technology called Adobe Content Server 4. Sony and a number of other online bookstores--most notably Borders--sell commercial titles in ePub/ACS4 format, and some libraries let patrons check out ePub books. As of early October, 17 e-book readers supported ePub and ACS4, making that combination the closest thing the industry has to a standard for DRM-protected books. Aside from the Amazon Kindles and Foxit's eSlick, all of the e-book readers in this collection of reviews support ePub/ACS4.

We compiled a comparison chart of the five highest-ranking e-readers at the conclusion of our evaluations. For the details, see our Top 5 E-Book Readers chart. And for individual reviews of the seven e-readers we put through their paces, click the links in the list of products in the floating contents bar on this page (above right).