8 or 16GB is too small
The problem is that apps such as the BBC's iPlayer and Sky Go do not let you save the TV programmes or films to SD cards - you have to save to the internal memory. With the amount of crap that Samsung force upon you (I know, I could root it) I regularly run out of space on my 16GB phone. It will be the same for this tablet. I would always suggest 32GB as a minimum.