I think techwise Kobo has best readers (with their TypeGenius, customizable fonts, water-proofing and light that can be easily adjustable and closable) but their shop is, understandably, focused at their own readers.
You shouldn't buy from Kobo if you don't have a Kobo. For independent devices buying from Amazon and converting is the best solution. It is very easy on the Mac with a simple folder action. Books are downloaded to this folder: ~/Library/Containers/com.amazon.Kindle/Data/Library/Application Support/Kindle/My Kindle Content
So, just use this folder action:
http://cl.ly/0i0R2h2O3W1c (you might need to reset the folder)
It will copy .azw files to your Download folder everytime you download one from Kindle for Mac app. After that, search for Apprentice Alf.