The only romance I can see is... Jean -----> Mikasa ------> Eren (?)
Yes, Mikasa has a huge devotion for Eren, but he doesn't care so I prefer Jean x Mikasa even if is impossible :P
anyways I think is too early for show a pairing and with all the destruction there I don't know if Hajime will...
My favorite is Armin ^^ I know that everybody thinks is weak and a crybaby since his first appearence but I feel this kid really have a huge rol in the story for to solve the riddle of the titans
and my second favorite is Jean, this guy is a jerk XD hope he doesn't die...soon.