All religiouse organisations see themselfs as better than other religiouse organisations.
I haven't stuided every single religion on the planet so I can't make a blanket statement covering them all but it has been my observation of most religions that I have had contact with or know a little about...they're judgemental.
They may preach love, mercy, helping mankind, but in the end to be saved, go to heaven, live in paradise, whatever, you must believe and accept their way...the only way to gain salvation or god's blessing. If you do not accept their beliefs, then you will face destruction, eternal damnation, whatever.
Some religions are more benign than others, but when stripped down to the essence of their beliefs, it's still there.
Back to the original question: What makes JWs worse than (most) other organizations (I take that to mean religious organizations)? Like James Woods said...the blood doctrine that forces parents to martyr their children to prove their faith in their god organization. Even the vengeful Hebrew God hated child sacrifce, yet the JW God Jehovah revels in it.
The DFing with subsequent shunning is probably the next worst thing. To cut off parents, children, siblings because they choose to not follow in their footsteps regarding faith and religion is a cult tactic to keep people in line, not a biblical edict.
JWs may not be the worst among all religious organizations, but they're certainly not benign. They are dangerous to people who accept them as God's channel and give it all authority.