Well, you know, back in episode one, the movie episode, I think I liked Yuki better (probably due to excessive Mikuru fanservice, that bunny outfit looked a bit... well... too much for first episode
) But Yuki's costume had style and it was kinda sexy the way her leg was showing in some scenes. And she was pretty and quiet.
But then, episode 2 came and Mikuru's appearance was beyond words, and she just clicked... or was it Haruhi's remark "loli with big boobs" and Mikuru being abused (I'm a sucker for maidens/damsels in distress) that swayed me?
It's probably the whole moe, soft spoken package along with the rest. Well, anyway, Mikuru's my favorite