If you are newbie to crypto (and not tech savy) you quite fast discover btc transactions are public, then you might look for an alternative and you go to coinmarketcap and see Darkcoin (and you hear it all over as well). That's the exact reason why Darkcoin will be picked instead of XMR, most people will not research fully and they are satisfied with easy solution.
Therefore it is crucial to have higher marketcapitalization than Darkcoin IMO so that Monero will be the easy solution.
I'm sure some will have the coin market cap in mind when searching for a coin, but I think a larger set of seekers will make a few google searches for "most private coin" or "most anonymous coin" and make their decision based upon what they find there. So, for their sake if their search brings them to this thread, I'll say this:
Any coin that uses masternodes (or supernodes or any semicentralized node) to mix your coins (Dash, Darkcoin) is at least semicentralized and if the same entity (government, hacker, etc) owns the series of nodes used to mix your coins, they can trace your transaction, making that transaction non-anonymous and traced (this also can be said of TOR traffic, but not I2P traffic, see
https://geti2p.net/en/comparison/tor). Whereas Monero is 100% decentralized and therefore not subject to such tracing.
Thinking of using BTC mixing services? Those can't guarantee 100% untraceability since all BTC transactions are in the public ledger. They can only highly obscure the transaction. Now there are specialized companies whose speciality is tracing BTC transactions. As they get better at what they do and as technology progresses, "highly obscure" transactions today could become relatively easily traceable in the future...and that would affect ANY past transaction since all transactions are on the blockchain. See
https://www.elliptic.co/law-enforcement/ for one example.
Thinking of using Zcash? That has several problems, including that it requires a trusted setup. You can see the list of problems here:
https://blog.okturtles.com/2016/03/the-zcash-catch/Monero does not have a trusted setup and is not affected by any of the shortcomings mentioned in the above link.
Only cryptonote coins (Monero is the clear leader) are untraceable, private, fungible, and secure. If you're going to use a private/anonymous coin, use the best. Use what will actually keep you untraceable and private.