To start off, this isn't an article meant to badtalk Sam, I was just thinking about why I don't like him as much as I like Dean.
What got me thinking was a pick on the Winchester Spot link
The options were:

Dean's ability of protecting Sam at any cost <3
Dean's unique style
His looks ;)
He's a tough guy / bad-boy
Dean's humor XD
All valid reasons why I like Dean, but none of them really explained why I didn't like Sam(not that I hate him!). He's intelligent and brave; handsome and charming. So why don't I like him as much?

When I thought about it for a bit, I realized that I could pinpoint the exact reason that I didn't connect to Sam the way I do with Dean.
In the Pilot episode, we learn that Sam left his family to go to college. Intellectually, I can understand his desire for a normal life. Who wouldn't want to escape the pressures of a hunter's life? Especially if they felt they were never given a choice. However, on a purely emotional level, it's much harder for me to swallow. Family is the most important thing in my life. I cannot imagine going a week without speaking to my sister, much less years. And yes, I realize that Sam would have continued speaking with his family if John hadn't flown off the handle. But even if John hadn't, the odds of them keeping in close contact were slim.

The other thing that created a strong impression in the pilot is when Dean shows up and tells Sam that their dad is missing. He tells Sam he thinks John's in danger and asks him to help find him; Sam says no right off the cuff. If it were my dad, regardless of the bad blood between us, I would have dropped whatever I was doing and gone after him. Dean practically has to beg for Sam's help before Sam relents.
Dean: "I can't do this alone."
Right there Dean is being completely honest with his brother. Emotionally, he can't handle searching for his lost(and possibly dead) father on his own. Now Sam is either ignorant of what he means or chooses to interpret it as meaning that he physically isn't capable of getting the job done. So he says: "Yes, you can."
That just got my hackles up a bit. It forces Dean to cover up his emotional vulnerability by being somewhat flippant: "Yeah, well I don't want to."
Sam seems either completely ignorant to the emotional distress that Dean is in or completely callous to it. I think, at that point, he was probably just ignorant. He viewed Dean as being the tough guy- after all, Dean was careful to present that facade to him when they were kids in order to make Sam feel safe. But nonetheless, it created a somewhat negative impression of Sam from the beginning. Even after they don't find John and realize something big is going on, Sam is still unwilling to sacrifice his normal life to help his family. It's only after Jessica is killed and all semblance of his normal life is literally burned away, does Sam choose to go with Dean.

I'm not saying that his reasons for those choices weren't valid, all I'm saying is that if I had been in his shoes, I would have made the choice that Dean did- staying with my family regardless of my desire for a normal life. So therefore, I just relate to Dean more than I do Sam. I realize Sam's changed, but the impression he made on me in season 1 has colored everything he's done since then. So in conclusion, I connect with Dean more than Sam because it is established early on that his love for his family is as visceral as mine is for my own.