The next Avatar, after Aang. Sokka likes Korra so far, since she's a lot like him personality and interests. Not to mention she's a fellow member of the Southern Water Tribe. And hey, she's pretty too.
In another lifetime, Sokka occupied the role of the Avatar after Aang, so he feels like he has a certain 'connection' to Korra, even if it may be an artificial construction of the Malnosso. He has yet to reveal this, though. It would be too weird.
Korra
Legend of Korra
Korra //
First meeting: July 9th, 2012
Relationship: Future Person