Personally I think it is 1914 and the following " This Generation " doctrine.
This particular doctrine went right against Jesus's own words of " No one knows of the time not even he "
He also admonished his true followers to not set a time upon god's own sacred time .
The leaders of the WTS even back to the late 1800's set a time calculated on their own theology 1874 being the first time set and proclaimed by C T Russell, also proclaiming 1914 would likely be the year of the final day of judgment Armageddon.
All throughout the 20th century the WTS held to this doctrine but was eventually revised of course when it was realized this generation had passed away who saw the events of 1914.
The overlapping generation doctrine which was devised to further uphold 1914 is not supported by the bible either.
The reason why the hundreds of other Christian based faiths didn't say anything about 1914 is because it is not supported in the bible and could be considered apostasy.