I've studied this issue for a while and conclude that, for me at least, I became a JW because I had a hole in my soul and needed to fill it. I filled it, or so I thought, with God. That seemed a reasonable response at the time. I viewed religion with suspicion, for lots of good reasons, and bought into the Witness argument that theirs was a very different brand of religion, or, as the brother who studied with me kept saying, "It's not a religion, it's a way of life."
That's why I've stopped kicking myself for the decision. I had a need and, hey, it worked for me. It's a form of addictive behavior, which is just a way of abusing something that, in moderation, might actually be good for you. Example: a glass of red wine a day is good for your heart. A BOTTLE of red wine a day? Not so good.
I've come to think that religion is like that, too. In moderation, religious beliefs may be beneficial. But once you start to abuse the substance, it in turn abuses you and you're out of control. "Moderation in all things" is one of the first biblical principles bible thumpers lose sight of.
It turns out my need was not for religion but for spirituality... and they are not the same thing. I am learning and exploring that now, and my life is infinitely better.