I can see why Brian is the way he is, so I don't condemn him, and Justin botched up a few things in S2 as well (e.g. kissing the virgin on the mouth). I completely agree about: "A is guilty and poor B had to suffer!", however I can't help but remember that he didn't have the benefit of the loving family upbringing Justin has had.
However, like you I feel more for Justin. Brian's built that take-no-prisoners hard outer shell, while Justin doesn't have one. Brian is older/more experienced (obviously NOT when it comes to romantic relationships, but generally speaking), while Justin is only 19. I agree that the bashing has made Jutsin less confident than he used to be, made worse by the fact that no one wants to talk about the bashing.
It's depressing when I read qaf fan accounts suggesting that ALL fault lies with Justin, that Justin doesn't deserve Brian, etc. We all have our favourite characters, but a bit of objectivity would be nice.