Enzo,you proclaim yourself a gainax fan and yet Gunbuster isn't on your list?
I am disappoint
The 2 seasons add up to 12 episodes,so it is short.
Another short gainax one would be re:cutey honey (if you don't go hardcore and watch the original 1973 version like I did lol)
edit: on second thought my reaction to cutey honey was "no wonder gainax did something like panty&stocking" so it might not be be a good idea for you to watch it