That's like making me choose between my children or something. I'm serious!
I have emotions for all of them. Sammy is my baby and I love Dean too. Castiel is so cute because he doesn't understand humanity (I hate what they did to him in s7 though. Lame.) They all have so much in common despite being so different. And of course I love Bobby so much! Bobby is the one character that I think nobody in the fandom hated. Everyone loves Bobby. He's just a gruff grumpy old man and the one with the most common sense.