Installing Koreader on Kobo is a 15 minutes process, it is quite simple. It combines both kobo and kindle good stuff, like
vocabulary builder , reading stats, sending books wirelessly and many other features. And the best advantage of Koreader to me is reading pdfs smoothly. If you have that in mind maybe Kobo is better.
Concerning using Kindle Mate on Mac. You can use Windows emulator(wine). It is useful.