Choosing an eBook reader

I spent the past week trying to trying to decide which eBook reader to buy, both for myself as well as for my siblings. C. and I have had a Kindle 3 (now called Kindle Keyboard) for over a year now, and it's been very nice, but the keyboard interface is driving me crazy. So, I have been looking at Sony PRS-T1 and Nook Simple Touch, and -- to some degree -- the Kindle Touch. As always, all three have good and bad points, so the trick is deciding which has the most good points. Since this turned out to be a really long and involved process, I placed it behind the cut below, for those interested.