I agree with OrphanCrow and JookB that Blood is the no. 1 dangerous doctrine. Many deaths result in this obscene,confused and petty test of obedience . Death can never be undone OR forgiven by the victim, which is why it sits way above all other issues. Child abuse sits at no 2 for me. In this I include all forms of abuse - sexual, physical or corporal punishment through to the cruelty of insisting kids sit through unsuitable, inappropriately violent or sexual Old Testament talks with threats of violence should they be unable to keep still/awake etc. I also include in cruelty the relish some JW's have for saying NO and depriving kids of fun like birthday cake and gifts or school Xmas performances. Another form of child abuse is the constant threat of withdrawal of parental love should the child not 'perform'the JW role to approved standards.
I agree that unquestioning obedience to the slave is a prerequisite to all the dangerous doctrines on the list but I'm going for the current specific and potentially changeable doctrines - as of course without obey the slave doctrine, well, the JW's would cease to exist!!