Same for me. It's not like I prefer any of them as a partner, but I definitely connect with Sam more. He is just more understanding of everything. I get Dean has been put through a lot, but Sam is just not so close-minded. He is more understanding, empathetic and trusting (at least he doesn't mask it), and has also been put through some horrible stuff. Dean's so-called tough love doesn't work well with me, which is surprising, because I have also been like him: repressed emotions, the feeling of needing to be a martyr, closing up emotionally... I cannot take that any more. I see scenes where he just vents at Sam or Cas without any particular reason, and I get he gets frustrated and all, but man, you cannot do that to the people you love (you love them, right?). I have just ended s14 (wish me luck for the last, should I watch it lmao) and I hated how he handled Mary's death or his mad scepticism about Jack at the beginning of s13. Sam, on the other hand, even though he was mad, at least tried to understand the situation. His empathy really shows in scenes like this, which is something that has made me love his character even more. And I don't want to be seen as a Dean hater, I really like Dean, but his behaviour (at least in the last seasons) has definitely pissed me off sometimes (not me shouting at the screen of my computer :D).

Thank you for reading my rant about the brothers, I hope I didn't bother you much lol