1. Audibility. I know for certain that my BTC is safe, sitting in a UTXO that everyone in the universe can see. Counterparties can verify the provenance of the coin.
With Zcash and Monero, you face the risk of (invisible/unknown) inflation (a property of an unauditable supply), protocol bugs (such as failures in the zkp) and counterparty rejection due to lack of coin provenance. This risk affects the market price.
Both these scenarios have happened, and could happen again. The first generation of ZEC had a broken zkp, which could be traced back to errata in the academic paper. [1] XMR (and other CryptoNote deriv coins) were failing to check for low order keys, so you could 8x-spend tx's.
2. Lack of exchange exchange support for US people, eg: real USD into XMR. 'not on coinbase'. * Kraken does XMR, but they also do not have a bitlicense (NY residents are blocked). * Gemini only has ZEC
[1] https://electriccoin.co/blog/zcash-counterfeiting-vulnerabil... [2] https://jonasnick.github.io/blog/2017/05/23/exploiting-low-o...
Bitcoin's ledger is a dream come true for financial investigators and tax collectors, if there was one thing a government might decide to ban entirely (and I don't accept that governments can't ban crypto, of course they can!), it would be privacy coins.
For most people though, I think the brand recognition is what does it for Bitcoin
That said Monero is my favorite cryptocurrency :)
Certainly not for buying goods and services, as no one outside the black market uses Bitcoin for that either.
(I'm mostly kidding, I don't think anyone can deanonymize Monero)