There must be something special in the Winchester bloodline to have had Sam and Dean last for 15 seasons, still resilient despite the magnitude of challenges they have had to face. After learning that a cupid was tasked with making sure that the Campbell line (the hunters) and the Winchester line (the Men of Letters) crossed and created Dean and Sam, we know that theses families are special. Although the brothers carry both the hunting gene and the Men of Letters gene, we see Dean more strongly representing the hunter, and Sam representing the intellectuals/Men of Letters. A perfect match.
While Sam and Dean have added many honorary Winchesters to their line, two stand more than others: Bobby (an adopted father figure) and Jack (their adopted son). Join us as we rank the Winchesters and see what makes them extra special.
10 Dean's Daughter, Emma
After a one-night stand with Lydia, Dean becomes a dad. His daughter, Emma, grows up quickly. In a few days after she's born, she's a teenager.
As an Amazon, she must kill her father and feed portions of him to other Amazons. For a minute, Dean thinks that Emma is different and could change. However, that may be a trick, and Sam quickly kills his niece, chiding Dean for not doing it himself. Emma isn't completely recognized as a Winchester, but she's Dean's daughter. A good hunter, she may have been, but a good person? She didn't have the chance to become.
9 The Campbell Cousins
In Season 6, we meet the Campbell cousins, raised to be hunters and working alongside a resurrected Samuel as well as a soulless Sam (although no one knows that at first). We only get to know Gwen a little bit, and the other two we don't really get to know at all.
While the cousins were raised to be hunters, they don't really seem as adept at it, and none of them lasts past Season 6.
8 Adam Milligan
Adam is John's son, Sam and Dean's half brother. He is the elephant in the room--still stuck in Lucifer's cage since Season 5 when he agreed to be Michael's vessel (the angels' back-up plan after Dean refused). Largely forgotten by the brothers, we definitely want to see him back.
He seems a decent person, someone who sticks to his beliefs but also listens to reason. However, he was never trained to be a hunter, and we didn't get to know him long enough to know more about his character.
7 Henry Winchester
Sam and Dean have been lucky enough to meet both of their grandfathers through magic and resurrection. Henry is their paternal grandfather and part of the Men of Letters. John had believed that his father abandoned him.
However, we learn the truth--being a father was important to Henry, but tasked with a mission to protect the Men of Letters knowledge and pursued by a demon, he wasn't able to return to John. Henry is amazing, almost like a Superman of knowledge. He proves that an intellectual can be an asset in any fight. Henry knows how to time travel, how to fashion a devil's trap into a bullet, and more.
6 Samuel Campbell
The other grandfather is Samuel, their maternal grandfather, and he is a hunter. Samuel does care about his family, but none more than Mary, which is the reason he compromises his morals and works for Crowley. He had been promised by Crowley that Mary would be brought back.
Still, Samuel is a brave and smart hunter. He has knowledge beyond Bobby on certain topics. For instance, he knows how to reverse someone's transformation into a vampire, that is if that someone hasn't fed on blood yet. His know-how comes in handy and saves Dean.
Jack, the son of Lucifer and Kelly, ended up being the son that Kelly had imagined and protected. He was kind and compassionate, generally a good kid. Attached to Sam, Dean, and Cas, and considered by them to be their kid, he looks up to them. He sacrifices himself again and again to save those he loves, just like Sam and Dean.
Apart from his character (that is, his character when he had a full soul), Jack has amazing powers due to his unique lineage. His powers even frighten Chuck/God.
4 Mary And John
Mary and John complement each other so well, so that it is hard to separate them. It's clear to see why the angels wanted these two together. Mary, raised a hunter, is an amazing hunter. Unlike John, she keeps close with the other hunters (John keeps on having fights and falling out with hunters). She develops a solid network and community of hunters, a skill that both Dean and Sam inherit. In addition, as a spirit, she still protected her boys. However, when she's resurrected, she has a hard time connecting with her sons, almost preferring the idea of them to the actuality.
John loves his sons and would do absolutely anything for them. His devotion is key to his character as it is what led him to becoming a hunter, devoted to revenging Mary's death. John also acquires knowledge and shares it with his sons. He's a good hunter, although often more solitary than most. On top of everything, he is a man of strong character, able to resist hell's plan to turn him into a torturer.
Not only was Bobby a great hunter, he was extremely knowledgeable and an excellent researcher. Matter of fact, he maintained the large network of hunters, knew who they all were, helped them with their aliases, and knew when something went wrong. He was a fountain of knowledge for all.
Bobby loved Sam and Dean like sons. Once when Dean tried to push Bobby out of a family matter, Bobby called him out, saying, "Family don't end with blood, boy."
With the brothers, it's hard to rank which one is the better, because both Sam and Dean are great characters and hunters. Sam seems to follow his father's lineage more, the Men of Letters, as he's an intellectual, a keen researcher, and a connector. While Dean can be quick to judge, Sam sees the world in shades of gray. He is the more compassionate of the two.
However, Sam has slipped in his judgement often, partly from feeling misunderstood and ego. He has sided with a demon over his brother, caused the apocalypse, and in alternate timelines--became the big bad. Now that his bullet wound connects him to Chuck/God, he sees what he had become in other story attempts, and what he still could become.
While Sam is the more compassionate of the two and it takes Dean awhile to trust, Dean commits to people, even to vampires like Benny. Dean favors his mother's side as he is very much the hunter. He may not have the book smarts (although he does have those, too, just in a smaller dose than Sam), but he learns on the job. Over the course of the show, he's invented several weapons like the salt gun.
Although he has a tendency to be stubborn, the allies frequently feel more of a connection with Dean than Sam like Crowley and Cas. Everyone wants to be his friend, which should tell us of the ultimate value he has in their eyes. He also has a wicked sense of humor (more so in the earlier seasons), but in a world so dark, we all need to laugh and shine a light.