I almost disagree about the Nook software. Except for the grayed out dictionary I prefer it to the Kobo software. I don't think it's as good as the Kindle software.
The Kobo software offers a lot more features and finer tuning of those features but I've found that (A) that doesn't really mean much to me and (B) those extra features don't work on a lot of my side loaded books anyway.
The Nook has far fewer features but it has the important features and you really don't have to think much about them. They're just there. I particularly like the way it gives me pages left in the chapter. That's a wonderful feature. And this latest firmware release seems solid to me while the Kobo firmware is fairly buggy. No show stoppers but there are things that just don't work all the time.
I also agree that if they made the Kobo Aura with a modern screen it would be my first choice. And if it had the Kindle firmware I probably would use it most of the time.
The problem with the Aura is it's screen. When I put it side-by-side with a Kindle or Nook it's not even nearly as good. However when I'm reading with it it's just fine. It's kind of like thinking about how good Jennifer Lopez looks, as long as she isn't standing beside Ellen Pompeo.
Barry