Amazon's Kindle Oasis is the company's flagship E Ink e-reader for 2016. The Oasis is the thinnest e-reader yet at 3.4 mm - expect for a bump on the side, which Amazon says makes it easy to hold. The display is the same 6" 300 PPI one used in the Kindle Voyage, but it has a brighter front light. Battery life is several months (if used with the external battery cover).
E Ink display info:
6" 300PPI E Ink