Why do I like Sasuke? Because he doesn't do what everyone else does. He follow what he thinks is the best approach and what he find is the right path. Sasuke is pure. There are many people that try to get in his way and follow their idiotic ideals, but Sasuke is not a push over. Sasuke is not the common man and he's not s naïve to believe that eternal peace will exist.
His dark attitude just adds to his personality in the best of ways. Many people adore the cliché shounen hero who likes to do the right thing and "protect their friends" which I have seen enough to the point that it dies of boredom. Sasuke adds fuel to this manga. He adds a sense of shock value and amazement. You also never know what is going on in his head. You never know what move he will make next. Being a mysterious character that hides his feelings is probably one of the best type of characters. People who like to stick with the one trick pony type of characters are probably kidding themselves.
You also have his fighting style, his cool and dark aura, his character design (he likes to change up his look instead of keeping the same boring uniform on), his goals, his history and his clan, his drive, his persistence, his achievements, and his development as a character are many reasons why I like him. He's determined. I don't blame him for betraying the village for his revenge. Letting the victims roam free and staying nurtured in a baby village won't get anything done. When Sasuke achieves one thing, there's always a new step to fulfill.
Sasuke also doesn't yell and act obnoxious. He is quiet and to himself. He gives people their space and he doesn't bother anyone.
Sasuke is probably the most interesting character in this anime/manga.