It seems that religions should be judged by their contribution to society. Some religions, while flawed like the Witness religion, do some amazing things to better society. Building hospitals, feeding the hungry, charitable works, sponsoring institutions of higher learning are a few examples of good things that many religions do.
Religions should also be judged by their contribution to its individual members. Are individuals encouraged to educate themselves, care for the community, be involved in environmental and social matters and to build lasting relationships. Many religions do exactly that for their members.
Conversely, the Witness religion does none of those things. It cloisters its members from society, it looks at the community as either an enemy to be destroyed or as a population to convert. It takes a "god will fix it soon" approach to everything causing its members to live life with a short-term perspective which typically harms the economic, health and educational prospects of its members.
So by these general standards its seem that Witnesses are less legitimate than most other religions.
zarco