The similarities between the Jehovah's Witnesses and the Churches of God (Armstrong era) are strikingly similar. That is particularity so because of our heritage as faith groups that have ties in the William Miller fiasco. The JW's are just as secretive and manipulative in its teachings and administration as the Churches of God are.
Both share similar aberrant doctrines,
Both have abusive teachings,
Both shelter pedophiles and abusers in their midst.
Both practice shunning (disfellowshipment).
Both have top down structural government that welds powerful authority
over those 'less than' below them.
Both are secretive.
Both ridicule medicine.
Both have a distorted view of Jesus.
Both ridicule apostates.