If everyone can define cults as they wish, then there can be no consistent definition of the word.
Many religions in their infancy are called "cults" (ancient Christianity for example) because they take an existing religion, add to it and have a charismatic leader, or leaders, who add their interpretations or commentary, thus defining the new "output" religion or sect.
Jesus introduced NEW doctrines in Christianity, and NEW interpretations of existing scripture and prophecy. Many of the Jews, even today, complain that Jesus hijacked Judaism and added his own spin as to what the Messiah should be and do. Armageddon is a good example. According to the prophet Zechariah, the Messiah will be a Savior of his people because he will protect the Jews from their enemies. He would be a political and military leader, roles Jesus has not (as yet) fulfilled. Many Jews expected the Messiah would save them from the Romans. A great force from the North comes upon them and desecrates the Holy of Holies. The Mount of Olives splits in twain and the Jews rush in to meet their Messiah. Unfortunately for them, they didn't understand that the Messiah would also save men from their sins, and that a third temple would first have to be built before the final battle.
Even today, many Jews think Jesus and his followers were a cult. The Romans considered them a cult, especially the intellectual class.
The Jehovah's Witnesses laid their foundations before Israel became a nation. As a result, they completely screwed up the Armageddon prophecies to where Jerusalem and the Jews were "spiritualized" out of existence and replaced by a small, man-made cult created in the United States around the turn of the century (19th Century). Now when JW leadership states -- with a straight face -- that the world's nations will one day declare all-out war against the Watchtower Bible and Tract Society, and that Jehovah will save his people and destroy those wicked, worldly nations, rational people say, "Why would the nations of the earth want to declare war on a Brooklyn publishing company that prints bad Bible translations and small, poorly written religious magazines?"
Ummm...yeah...that makes sense. But the original prophecy of a great gentile power coming out of the north to beseige the city of Jerusalem and the Jewish people make for a slightly better story. Both have been at the center of a raging political and religious controversy that has lasted for millennia. Besides, the scripture says "Jews" and "Jerusalem," and "Mount of Olives." It's the Governing Body that has changed these things to mean "Jehovah's Witnesses" and "Brooklyn" and "Paradise Earth."
So, are the Jehovah's Witnesses a cult or an eccentric modern wacko religion?
I think it can be both.