This is a really interesting post - Certainly intrigued by the background aspect, and its an interesting exercise in exploring what about oneself makes you lean a certain way, so here's my go at it:

Outside of the actual evidence and info related directly to this case, here are my experiences that lend themselves to my outlook

• I am a believer of Adnans innocence. I don't have a theory of what happened, but I simply don't believe that "If not him then who?" is a valid reason to believe in his guilt in this case, given the circumstances
• I had spent some time previously researching the Ryan Ferguson case, a young man wrongly convicted and imprisoned for over 10 years due to a false confession of his friend. He's finally out and after listening to Serial, he wrote this op ed about his experience listening to Serial and how he related to Adnan. I put a lot of weight in his perspective because, as much as the rest of us can speculate what we would or wouldn't do in a given situation, this comes from someone who has been wrongfully convicted and spent a decade in prison. He knows how life is in there, how people think in there and, in particular, how innocent people in his situation might operate.
• In college, a good friend of mine believed her bf was cheating on her (and as it turns out, he was). There were many opportunities where she could have done one thing or another and known for sure, and I had always encouraged her to, so she could know for sure and leave him, but she never would. She didn't want to know for sure because she didn't want to be forced into the situation of knowing she'd invested all of this time with someone and it was wasted. I always found this incredibly frustrating because wouldn't you just want to know the truth, and not lie to yourself? In a very strange way, I felt the same way about Adnans case. It would have been so easy to have the police have Jay call Adnan and either have him implicate himself or prove he truly wasn't involved. All they had to do was have Jay make a call and say "Hey, the police are going to question me. What should I do? What should I say?" Had they done this and gotten Adnans response, one way or the other, none of us would be here on this sub discussing this case. It was just so easy, and they didn't do it. My belief is they didn't because, like my friend, they didn't want to know they'd wasted all this time on a guy that wasn't the one.
• In my hometown, a young girl was abducted and murdered on her way home from a friends house only a few blocks from her own. The case gained national attention, mainly because they were able to identify the stranger that grabbed her (and ultimately murdered her) because a closed Car Wash security camera actually captured when the abduction happened. The man had no relation to the girl and chose her at random. Had that video footage never existed, the actual culprit would have likely never been caught and I'd guess her mother may have had a lot of scrutiny on her, due to some of her own run-ins with the law. This case is much different than Adnans, but I think what it instilled in me is to never discount the 3rd party theory

I'm sure there are some other reasons, but those are the top of mind that come to me.

I just want to say thank you for this post. This was a very insightful exercise for me and I'm very intrigued to read through others responses and hear what they have to say as well, because so much time is spent arguing what our position is and the 'evidence' in this sub, so little is spent really digging into what in our past makes us lean one way or the other.