He reads just about anything but I'm not inclined to make an investment in a device that wouldn't include graphic novels and similar color content. I just don't think it would last.
I read a lot of comics, but I also read a lot of regular books. For now, I read using a 10" Chuwi tablet because it gives me a decent, color screen, at a decent size and weight, at a reasonable price.
I would LOVE to have an eink reader that could fulfill this role. I have been watching and waiting for years.