I think it was a combination of this site, the Watchtower Library and some online ministries for me, that finally brought me over the edge
I've always had doubts, people that made me really think were a set of pioneers/elders in a congregation who posed difficult questions where the Bible and Watchtower doctrine don't match. Surprisingly they're still JW's to date, but they had raised serious doubts. They believed their own logical conclusions were wrong and they didn't study hard enough, these were people that were dedicated for pretty much most of their life, they had part time or no jobs, lived in a trailer and they couldn't understand it, why would I be able to.
One day I got a call to make a talk about a bible verse that night, the person that was scheduled couldn't do it, the Watchtower Library was only on Windows and I couldn't get it to work on my Mac, so I went and looked online, I found a discussion on this site on the topic and then some other online ministries had full bible-reasoned sermons on the topic. I copied a sermon, modified it a bit and did the talk.
I then got a talking to from the elders, I said, it was wholly reasoned from the Bible, what was wrong with it. They said "the Bible verses weren't wrong but your explanation wasn't from the Watchtower". I said "I quoted literally from bible verse to bible verse" and they said "you can do that research in your personal study, but in a talk you should quote what the Watchtower publication says, not just the Bible". That started me thinking and brought me down the rabbit hole that is this site and other sites like it.