I'm not particularly aggressive... I'm just right.
I'm not sure if the capacity really matters. I like my 32gb version... the black ones look cooler, but if you are going to do a whole library of games, you'll need an external hdd anyway and unlike other systems the wii u doesn't really care where you install games/dlc/ect.
Since I've got the bulk of the good games on disc anyway (no need to back those up atm) what I did was just stick a 64gb thumb drive in the back of my wii u and I install a couple games on it at a time. Once I beat them I just delete the game (not the game save) and install something else. Of course if/when Nintendo's servers stop allowing downloads it will be harder to get/make game rips and I'll probably put a full-fledged hdd on it with all the games.