I have to agree with NonCoinCollector. There are good things I could point to from my time as a JW, but I could have gotten those from other religious (or possibly even secular) groups. And perhaps it would not have come with the baggage that I am left with.
Maybe the one thing that I could list as a benefit on some level, is that their teaching that death is the end of existence is much better than the notion of eternal suffering in the afterlife. I occasionally feel a bit sad at the idea of missing out, but that is far better than the terror many people feel over thoughts of hell. Even people who stop believing in god find that their subconscious fear of eternal torment does not go away when they consciously decide there is no afterlife.