For me, the changes stemmed from reading the Bible and being attacked for it, in my hall. Obeying God, rather than men and not caving or cowering to man-made doctrine and not hiding my contempt for Pharisaic behavior. Being dragged into the back room and "counselled" for speaking the truth (even having the elders admit "you're not wrong, but...") and exercising my God-given, Bible-trained - not WT-trained (1John 4:1) - conscience. Realizing the erroneous interpretation of FDS and "Be obedient to those who are taking the lead among YOU and be submissive" didn't allow men to seize control of my mind and heart was the catalyst for the distancing myself from the JW mentality (Pro 14:15). Coming to sites like this was a result, not the cause. I never intended to start any tension between myself and the people I believed were fellow lovers of God and Scripture. They picked the fights with me and attempted to coerce me into denying the Scriptures and the Christ in exchange for their "love" and approval (Mat 23:15). Fortunately, I'm not the typical loser with low self-esteem that most JWs are and didn't need their permission to feel fulfilled. I had the feeling of "Now to me it is a very trivial matter that I should be examined by YOU or by a human tribunal." - 1Cor 4:3
Repeated attempts were made - mostly by Watchtower study conductors, I realized - to force me to preach the literature, but I refused and would only base my ministry on the Bible (Psa 118:8): I made it clear "If the Bible doesn't say it, I won't preach it" (Pro 30:5-6). I quickly came to realize the main doctrine of the JWs is the hierarchy and total submission to men, which they deny exists. All other doctrines are secondary to "You have to believe whatever we tell you." It's impossible to avoid that doctrine, even on things where the Bible remains silent, because the totalitarian control exercised by the Society permeates everything. They have to weigh in on every conceivable detail and have decided there is no such thing as a "conscience matter" anymore (Eph 7:16). They have made hoops to jump through and lines in the sand to pick a side on (Eph 4:14-15), just like the Pharisees; yet they perceive absolutely no correlation. Likewise, Jesus pointed out to the 1st-century Pharisees "Isaiah aptly prophesied about you" and they still refused to see.
Just like the temples and synagogues were God's houses, even though power-hungry attention whores had taken over the leadership, I still attend meetings and consider myself a member. While I stand out like a sore thumb, have been "marked" and all but silenced from the ministry (their version, but the Internet is now my field), I feel I actually belong there. It's the vast majority of the others who I feel don't (Jer 5:29-31), so I'm not leaving. They'll have to throw me out (Isa 66:5, Luke 6:22-23), which I won't be surprised if happens very soon (John 16:1-4).