I believe there are worst teachings out there, but the Jehovah Witnesses affects more lives and does way more damage than a normally small size cult could. GB has cult membership thats claims people by the millions. And certainly they false teachings would have led to more deaths than suicide cults.
I personally was negatively affected by their teachings long after I stopped attending their meetings. I stopped going to their meetings in the late 90's, but it wasn't until late December 2004 that I discovered they had dirty secrets( false predictions and sex abuse) and false teachings(too many to count). And I have only accepted within the last couple of weeks that birthday parties are not bad. And its only now within the last several days that I am realizing that the WTBTS really is a cult!
This message board has help me to see things more clearly. I think I am a better person because of it. I do think for showing me all of this.