I did a little snooping around over various websites, to find out what is considered the best e-reader for which purpose. The results were not very surprising (at least not for me). Basically it all depends on where you live combined with what you are looking for. There is no real ‘best e-reader’.
When you live in the United States, the selection of e-readers is largest (which is hardly surprising). According to http://ebook-reader-review.toptenreviews.com/ the best choices are all based on Amazon’s Kindle equipment, with Barnes & Noble’s Nook in there as well. The Sony e-readers are among the least desirable e-readers, although they still score quite good. Interesting fact: Apple’s ipad is missing in their listing.
This is in bleak contrast with the Dutch site http://www.ereaderstore.nl/category/4863/top-10-ereaders.html, which lists the newest Sony PRS-T1 as the best buy, and the Kobo Touch as the runner-up . This for the simple reason that Kindles and Nooks are not (yet) available here. Also e-readers by BeBook and Archos are listed as good e-readers. Again, the ipad is not in the list.
And how are things in the land of the rising sun, Japan? According to http://blog.japantimes.co.jp/japan-pulse/which-e-reader-will-conquer-japan/, Fujitsu’s FLEPia e-reader has tried to make an impact, but still that has not proven to be a match for the mobile phones that people use everywhere to read and watch other content. Also Sony has not been able to get a strong foothold in their own country; most Sony readers are sold in the USA and Europe.