I would hazard that most consumers wouldn't be able to tell much of a difference with current hardware, especially as an e-reader. They don't tell us what they have or how much memory is installed, but if it is a convertable laptop with a touchscreen or similar then I would try Gnome. You will have a much better time for a simple e-reader.

If it is memory contrained, or ends up being an Atom processor then perhaps a lighter desktop might be better.