I think Sasuke cared for Kakashi more than he did Orochimaru, so you could say Kakashi. But, he did spend a longer amount of time with Oro. Honestly though, I don't think Sasuke actually viewed either as his Sensei. All he needed was the motivation and hatred for Itachi, which was taught through Itachi's actions and words. Even though Itachi never actually was his Sensei, Sasuke followed his words, which became his lessons.
First, Sasuke lived for revenge against Itachi, then he lived to obtain vengeance for what had been done to Itachi. That pretty much shows where his hate, love, and respect has came from (love and respect pretty much only for Itachi

) That's his true Sensei IMO.