As far as the arguing of aspect ratios: I only read comics on my tablet as mentioned. So I am not claiming any knowledge of the impact on reading books.
But for your standard, American-size comics (the bulk of what I read), the best is the 3:2 of my Surface. The worst was the 4:3.
On a 16:9 screen there will be black borders at the top and bottom of a page. On a 4:3 there are black borders on the left and right. But placing a 10.1" 16:9 tablet next to a 9.7" 4:3 screen side by side displaying the same page, the page is noticeably smaller on the 4:3 tablet.
On a 3:2 the borders are very thin. The pages fit almost perfectly. My Surface has a much larger screen than the other two, so a direct comparison wouldn't work. But I'd bet a 3:2 Surface Go would be better than a 10.1" 16:9 tablet or a 9.7" 4:3 screen.
Sorry if I'm boring you with minutia
