I spent a large chunk of last night moving my whole eBook collection into Calibre.
I guess you could count me an early adopter of the whole eBook thing. I started buying eBooks and breaking their DRM back in PalmOS days.
I also kind of prodded Manybooks.net into supporting Apple Newtons and pointed them up to the tools they needed to do the conversion back in the day.
Though Europe seems to have quite a few which atleast have no integrated eBook store and are designed to work with third parties. Such as the Onyx Boox and the like.
I personally use an old Sony PRS model. Though ive flirted with the notion of getting the Remarkable Tablet recently.
The kobo alternate firmware took me by surprise, as they seem to have eliminated all but two or three binary blobs, which is honestly very unusual in this space.
Onyx Boox and Pocketbook may both be worth looking at too, though they ship with google services.
Price is quite reasonable compared to the Kindle international edition. This is on my #tobuy list now.