well, i'd have to agree with the ppl saying he doesn't really "favor" anyone.......the reason he picked sasuke over naruto is probably cuz he knew he couldn't teach naruto anything useful.......like he said, naruto needed to know the basics first, and if he spent time teaching naruto what he should already know, he couldn't prepare sasuke for his match with gaara.

imo, kakashi knew that once naruto learned to control his chakra, he could pretty much take care of himself, and in the worse case scenario, the kyubi could always bail him out (like in the haku fight).

thats probably y he chose sasuke instead of naruto.....he's just being a good sensie.