I'll chime in - the Kindle Paperwhite I believe is the superior machine from a physical feeling and aesthetic perspective. The problem (for me) is who makes it. Amazon keeps locking it down so it's harder and harder to load your own DRM free books onto it, in addition to tracking everything you do on it (like sending all your reading statistics whenever you get online).

I have a Kobo Clara BW. It's still a great machine, but the Kindle is definitely superior for feel and visuals, but I use the Kobo 95% of the time. They are way more open with the software and I have mine in "sideload" mode (an official setting), which really just means that it doesn't make me log into anything and it doesn't even attempt to connect to the internet. Also, I can purchase a DRM free ebook on the train, plug a USB cable into my phone and my Kobo, and then load it on like that. Now I own my digital book, have supported the author with a larger margin, and get to read it on my more private machine.

Definitely not a no-brainer for everyone, but I'm happy with my Kobo.