
E-ink is better for chord charts because you can see it in direct sunlight. Both of the tablets have internal lighting for dark rooms.
I just got the inkBook yesterday. So far, I'm very pleased with it. It was easy to xfer my latest songbook (a PDF file) from my computer. The documentation is sketchy, so if you've never used an Android phone or tablet you might get confused. It was less than $200 at Amazon, including the case (a separate item).