I don't know which country you're in, which will affect price, but you might like to have a look at some reviews of the Samsung Galaxy Tab S2 8.0". It has a 3:4 aspect ratio screen (2048 x 1536px AMOLED) which should be a good size for reading. Not necessarily the most portable device though.
Caveat: It's a later model than my own 8" Samsung tablet so I can't give it a
based on personal experience.