I very consciously did not buy a Kindle when choosing an Ereader about a year ago. The Kobo H2O is incredible and has served me very well. The format support is wonderful, and the stock OS does more than I need (though there is a whole community of custom OSes that also look cool). Combined with Calibre, I don't even see what the Kindle value prop is.
The Kindle is inexpensive, has great support, has a huge library (open to non-US people with non-US credit cards), and you could just email a MOBI to it (which is great if the Kindle owner is your parent). It's only disadvantage was that it did not support ePub and so one had to go through Calibre. Now that Kindle is supporting ePUB and no Calibre-tion is needed, I don't even see what the Kobo value prop is.
1: The desktop applications don't auto-sync. (I really like reading books on my laptop because it holds the screen at a comfortable angle. This is especially the case when reading while eating or doing something else with my hands.)
2: Sometimes the Android app is buggy, requiring that I reinstall. When I reinstall, I have to re-enter all my preferences.
3: Some of the default settings in the Android app are dumb, like showing popular highlights. I always turn that off as quickly as possible.