Well, not necessarily.... Gurren Lagann and Kill la Kill happen to be my two least-favorite anime of all time, so they will never be a part of my anime collection, lol. I do own Code Geass, but have only seen about 8 episodes from it - it's just ok. Those kind of anime are just not my cup of tea...Yes they're pretty much essentials
Giant mechs with watermelon boobies would be awesome, even better if it was in a High SchoolAh well, I have fairly narrow preferences when it comes to anime. The things I highly dislike in anime are:
Comedy (totally sucks in anime)
CGDCT (No cutesy crap)
Fanservice (especially watermelon boobies)
High School setting
Sports or Game based (especially card game)
So that doesn't leave me a whole lot to choose from, lol...