Kara/Space. Kara is my absolute favorite when she’s just out in a Viper (or the Blackbird) kicking ass and saying snarky things over the com. I frequently see Kara/Lee as a sibling relationship. I love Kara/Sam, although I’m in the middle of rewatching the show and Sam is currently still on Caprica and who I like tends to shift with the show’s focus.
In terms of non-romantic relationships, Starbuck + Papadama (making up words as I go) is my absolute favorite. I LOVE them.