I have both iPad Air with Paperlike cover and a Boox Note 3C... and the Boox with its color eInk and Wacom pen is SO MUCH nicer to write on and read that it's really not comparable.

Also paperlike film for iPad significantly degrades the screen, making it darker and grainy. It's still a better all-around device, but its really not as good as these eInk tablets for writing.