I liked the Nook Touch but some issues have come up with it already. Nothing that can't be fixed by B&N. I didn't see any ghosting on the store model I played with. Of course it seems most e-readers have bugs that need to be worked out after they come out. That said I have never had a problem with my Nook Classic so I can't tell you how support is for them.
I really like my Sony 350 & have no difficulty reading on its 5" screen. I have Kindle3 & a Nook Classic & have no difficulty switching from the different screen sizes. Once again I haven't had a problem with either Sony 350s I have so can't say how support is.
I don't know anything about the Kobo but what I see from videos on it. Good place to ask about Kobo is in the Kobo forum. I must admit except for appearing a little slower, I liked what I saw.
Good luck
