Eh, I don't see Sasuke as a favorite at all. I think Kishi just likes to experiment with different characters at different times to even out the character ...er.. flavors? Instead of just Naruto, naruto, naruto. Sasuke is also Naruto's goal, a vicious part of the main character plot line, so it's nessacary to show Sasuke as much as he does. Plus, Sasuke is a interesting character, but nonetheless, Naruto will always be the main character, the shows called Naruto, and we've been seeing Naruto a lot lately. We haven't seen Sasuke in awhile now. So..
Plus., Kishi is telling a story, we can't really expect him to keep it all on Naruto without expanding the view a bit and going in deeper depths with other characters. If we don't know this ___ or __that that he puts into the story we may not fully understand it at the climax. Either or, whatever. It doesn't bother me.
540 also made me a bigger NS fan, cause she's seeing her feelings for him in a bad light.
There can be two main characters, three, four, it doesn't matter. If they're shown often, theyre main and improtant to the main plot story. Hinata, per say, isn't. She's a background / filler character, but still important in the subplot department I guess. Sasuke is the main bad guy, Naruto is the main good guy, sort of like spiderman and that octopus dude. Sakura is his Mary Jane.