It is good to hold Zcash for a long time and sell to buy btc, when the price increases. Zcash keeps on getting more popular and the progress of Zcash over Bitcoin can be seen directly from the zec to btc graph.
Zcash is currently quite warmly discussed in the atmosphere of the cryptocurrency industry which is full of speculation. In short, Zcash is an asset payment value where all sender names, recipient names and the entire transaction value are kept secret from the blockchain automatically. Only someone who has the "key" can only see the contents of the transaction content.
Zcash has its own approach for privacy, the same way Monero and Dash does. However, I believe that BEAM and Grin's mimblewimble privacy tech is far superior than other anonymous cryptocurrencies, because of the lack of addresses among them. Despite this, the technology is new and starting to emerge on the crypto market. Both BEAM and Grin would need time for growth before they could be comparable to the likes of well-established cryptocurrencies like ZEC, XMR, and Dash.
In the end, I guess that it's a matter of preference whenever someone wants to use one privacy coin from another. But in order to determine which privacy coin is truly private, one needs to perform a research on their privacy solutions.
Nonetheless, there's a possibility that both BEAM and Zcash will live alongside each other for years to come. Just my opinion