[nhedgehog]

I would recommend (great screen and folder management):

1) Pocketbook Lux 3 (great for reading, adaptable)

If you like less options but still eInk carta and folder management:
2) Bookeen Cybook Muse Frontlight (contra: very bright frontlight but inverted screen helps with this)

If you like to fidle a lot with the system and want to use it not only for reading, an open Android system could be worth looking at, since is more flexible. But only if you don't care about batterylife (a week is still possible)
3) Energy System Ereader Pro + (Eink carta version comes out this summer)