Only unkown is ZCash.
I think the biggest unknown is whether privacy for crypto-currency really has a big potential market.
I think the upside for Monero may come more from its CPU-friendly hash and greater decentralization (compared to Bitcoin's trajectory) than for its privacy. In that case, Zcash seems to have the wrong philosophy about distribution and
they have yet to announce their proof-of-work algorithm. I view Zcash mostly has a technology incubator. Ditto Monero's privacy. The boots on the ground feature of Monero is its distribution and CPU hash.
In addition, I think the importance of fungibility enforced on the protocol level (with privacy as by-product) is a bit underestimated. As far as I know, Zcash will allow both transparent and private transactions.