There's plenty of Monero competitors, but only ZCash has an actual community and adoption. And only Grin has good tech, deserving to go toe-to-toe.
But Grin's tech is already being implemented in Litecoin so I feel like MimbleWimble coins are doomed on arrival, and Monero will remain the most popular coin of its kind.
ZCash have no community. Not on reddit not here not anywhere. ZCash have founding company with rich strong owners. They make influence so ZCash was added on all exchanges and services. But there is no community.