he's pretty much raised Sam from the time he was four years old & Sam was six months old.

Agree with Dean-girlx,;-) Dean always take care of Sam and feels responsible for him because it's his younger brother and not only that he also took care of his dad when he was alive. He was just a little boy and already he had such a heavy burden on his shoulder and he kept that burden even still. And know this with lucifer/lilith and the angels, Poor dean they are giving him a hard time

it's hard to pick...so i won't :D i can't choose coz it's a tie - dean and john

it's a tose up between dean and bobby but i picked dean because for pretty much what dean-girlx said

just think..a 4 year old kid forced to become an adult, a parent for both his brother and his dad..it's a huge burden to bear for just a child who had the right to stay a child more than just 4 years..i admire and respect him for that!
next it's bobby, he's awesome!

idk, it was so hard because all of them have responsible qualities but they all act irresponsible at times, for me it was a tie between sam and john, though i picked the latter.

I went more on the aspect of "is" than "was". Dean was a highly responsible youth, and in his own way, I think Sam would have been too. I think John really tried; his priorities just got a little skewed along the way.

So that leaves Bobby! I don't know...Sam and Dean have both done some pretty irresponsible things as adults, but Bobby seems to be their rock. He's always there for them, nearly always knows how to help them and he's very experienced - just a great guy! So here's a vote for Bobby!!