SAM kinda ditched as we found out in the 1st season
JOHN forgot about his family when he became obsessed with the Y.e.d
DEAN is really the only one left, and he's always putting family first

No contest. Just what beffie said.

ok yeah he tried to leave when was litttle - but Sam gave evey thing to his family ! - he gave up all his dreams - never wonted to be a hunter he got draged into it - Dean useto like hunting - then hated evey thing about it - even when evey one left him he tried to keep fighting - not in the most good way - well in season 6 the tabels changed !

Dean, he was always helping ppl no matter what and doing what was right to help hi family as well. he cares and just wants what is best

Dean is like the family glue. That's his role.