Nexus 7 for Books
Nexus 10 for Movies
But if you have problems with the black levels, you should get an amoled screen like Galaxy Tab 7.7
I got my Nexus 10 today and came from Nexus 7. I have to say N10 is huge, N7 is a toy compared to it.
N7 is much more comfortable to hold and read, but its...