I need to read a lot and reading from PC or laptop screen is not a pleasure if you are in a bed ))
I want device that will replaces paper books and that will be as good as paper or better ))
As a reader you may face small size of text on screen.
If you look to books sizes they are usually 10" or 11" and has dimension ratio 1.2-1.5, with most common is 1.42 (which is √2 - A series papar size ratio).
It's better to have near the same ratio for tablet screen to efficiently reuse all available space.
I had N101 II tablet with 10.1" screen size and 1280 x 800px resolution. Screen ratio is:
1280/800 = 8/5 = 1.6
In portrait mode with full page on screen top and bottom space are wasted as screen is too narrow.
Full HD resolution has worse ratio:
1920/1080 = 16/9 = 1.78
but there are usually additional pixels for menu (like in Samsung Galaxy Tab A 10.1):
1920/1200 = 16/10 = 1.6
There is Samsung Galaxy Tab S2 9.7 that has ratio:
2048/1536 = 4/3 = 1.33
It is much closer to book ratio and provides more space for text in portrait mode that is usual for books.
Another parameter is DPI - how precisely screen can represents details. Usual print material has at least 300 DPI for inkjet printers and 600 DPI for laser printers.
CRT PC/Windows monitors has standard of 96 PPI and Apple monitors has 72 PPI. But those numbers slightly increased with LCD monitors have come to play.
My old tablet has such DPI:
10.1" / √(1280² + 800²) = 150 DPI
Samsung Galaxy Tab A 10.1 has:
10.1" / √(1920² + 1200²) = 224 DPI
Samsung Galaxy Tab S2 9.7 has:
9.7" / √(2048² + 1536²) = 264 DPI
So've I chosen to buy Galaxy Tab S2 9.7 for reading because of DPI and more appropriate size ratio. Even though it has a bit smaller screen it is wider in portrait mode and it's a bit better for displaying details.
Samsung Galaxy Tab A 10.1 spec.
Samsung Galaxy Tab S2 9.7 spec.