For privacy coin, it doesn't need to have too many functionality. It just need to do what it is supposed to do, and do it well. The tech alone doesn't dictate a coin success; the one that have already established itself with a high MCAP will have the better survival chance + with an active development team, can always copy over the advantage afforded by the lower MCAP coins that are popular with users.
A higher MCAP also affords better stability, decentralization, and liquidity.
IMO,
currently the best privacy coin is Monero (IMO), as it offers multi-layer privacy protection, including the fact that your IP is also hidden in such a way that anonymity btwn it and the transaction is granted.
However, there is a FUD going around about a Monero's "bug" exposing user's IP during the mixing process. However, that report is misleading, since yes there is a bug, however, it simply throws out random IP addresses w/o linking them to the transaction of that user itself -- and also a fix is already underway to resolve this issue. Hence in the near term, perhaps Monero's price will be affected; good time for me to pick up a few more XMR! Also even though the supply of XMR is a "potential infinite" as the mining rewards isn't reduced to zero but tails off; but once the reward have reached the tail end, the production of new XMR is negligible and is there to reward the miners and to keep the actual fees low.
Another coin that I find promising is
Verge Coin; despite of their recent screw up with the release of the WraithProtocol -- which I am sure the problems will be ironed out and eventually fixed.
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Dash MCAP = $4,819,865,825
Monero MCAP = $3,854,011,255
DASH have a higher MCAP than Monero, however the level of privacy afforded by Monero (described as excessive/redundant) is far superior; according to what I have gathered that is; and with the kind of active development team that XMR has, it will most definitely continue to improve and adopting whatever that seems to work well for other newer privacy coins out there.
See also: https://masterthecrypto.com/privacy-coins-anonymous-cryptocurrencies/ for a summary comparison between the various privacy coins.
