From having had several different Kobo models, mostly because I kept breaking old ones whose screen had a glass substrate, I'd say calling them Kobos "the best eReaders" doesn't mean much. The UI has gotten worse with time, in my opinion, and it's always been sluggish for every single device I've had. Something as simple as clicking on a number to go to a reference is painful. Most of the time, the touch is interpreted as a page turn instead, so you have to go back to the page you were reading and try again. If it works, you sometimes have to wait 15-20 second for the reference to open, and then you have to go through the same process to go back to the page you were on. It's just OK to use as long as you read nothing but fiction, which contains few or no references. The browser is unusable for anything but accepting the terms of service to connect to a WiFi network. Converting books to the Kindle format is a trivial operation in Calibre, so the ability to read EPUB is an extremely weak sales argument in my opinion. Last, I personally dislike how strongly the device is tied to the Kobo marketplace (I suppose Kindle has the same issue). I think the vast majority of owners of Kobo eReaders are unaware that they can read books from other sources (Google market, gutenberg.org, etc.).
Hopefully someday someone will release eReaders with good color screens, it might make the competition in that sector go up.