I have recently been thinking about this as it was a big life changing decision. Only now do i realize it wasnt about doctrine.
The reason was because i wasnt happy and didnt respect the elders and the congregation was made up of unhappy people.
I was always being lectured for being happy. When i had a study that came to the meeting i thought thats a good thing, and i was happy. But this wasnt so with the elders because the study didnt sit correctly and put his feet up on a chair so they wernt happy....oh i was happy when i met and displayed on my home wall a signed shirt of my favourite rock band..the elders wernt happy and said it was idol worship and asked me to take it down. ...blah blah blah i discoverd i was happy when i wasnt spiritual indoctrinated people, even if some were great people.
So i think thats why i left the witnesses and now i have more time to be happy....