I definitely prefer someone who has a back bone and will call me out on any BS. I prefer it is done assertively but not in a condescending way. I think it should be pointed out to me because I know I am flawed. If the person responds aggressively then I will probably respond in the same way and that won't solve anything. An aggressive tone turns me off very much and I will feel attacked.
I prefer to take the calmer approach that way I am able to have a conversation without arguing. If you try to make a point in the heat of the moment things get said out of anger that we may not really mean to say. I thinks its totally immature to get aggresive when trying to make a point.