I prefer techy, space opera animes, so here are my favs so far:
Robotech and
Gundam- classics
Knights of Sidonia- I really like the attention to real space physics, like gravity and acceleration. but it ended on an anti-climax on season 2. Where's season 3?
Code Gease- excellent plot, but I did fast forward through the teen high school stuff
Aldnoah.zero- mechs on rollerskates, but still good lol
Legend of the Galactic Heroes- I tried hard to like this, but it got too repetitive and downright pretentious.