If you don't mind me saying this, you have sort of "morbid curiosity" in this game, i.e its like you want to play it but at the same time you don't want to want to play it
I ain't bashing or judging, absolutely, but why don't you give it a try? If you end up not liking it you can simply drop it.
Linda and Sal are two side characters but become more important the more you follow the story, and you'll end up playing as Sal for part of it. That said, neither is saint (nobody really is...).
To clarify: your choices are not to be good or to be bad, but to give in to your dark side or to fight it