Current (and previous) generation Paperwhites have the same resolution as the Voyage and Oasis. I have a Paperwhite and the screen is fantastic. I'd love hardware buttons for page turning, though.

While the Oasis is expensive, if you add a nice cover to the Voyage you're close in pricing. Either go solidly midline with the Paperwhite or go all out with the Oasis, depending on your budget.