For me, I had doctrinal issues all along: The name Jehovah in the NT was first, later came the "thinking heart", stupid comments on evolution and age of the creative days, then the 1975 and refusal to man up to the false prophecy by the Watchtower - and, of course, I was close to the Dunlap brothers (and the Ray Franz issues) through that connection.
Plus, as I commented on Minimus' other thread about being happy after leaving - to be honest I was never really happy as a witness.