I gave up with reasoning doctrine and their teachings long before I left. The first doubt I had was when I was about 8 or 9 years old over the 1975 nonsense, but I was more interested in finding a way to get away with playing whatever I found cool at that time.
What made me leave has nothing to do with what they teach. I am born in, and I grew up seeing through their hypocrisy and not believing or applying what the JWs I knew used to preach. To me it was about how full of shit most JWs around me were, and still are.
I was never really interested in anything JW. It was something imposed on me since I was born, and I never cared for any of it.