Why does orochimaru want Sasuke?

Answer 1

Sasuke Uchiha has the 'Sharingan' ability, an asset that Orochimaru would find very useful.

Also, Sasuke is a very powerful Ninja, already adept at Taijutsu, Genjutsu and Ninjutsu.

Orochimaru has already managed to put a curse upon Sasuke, which lends Sasuke a portion of Orochimaru's power at certain points.

Orochimaru believes that by lending him such power, Sasuke will hunt for more, eventually leading him to find Orochimaru.

Another reason is that Orochimaru eventually wants to take over Sasuke's Body because he is so powerfull. once Sasuke kills Itachi, Orochimaru Plans to inhabit Sasuke's soul.