XMR provides not only anonymity but unlinkability as well.  I've used it; it works great.  The CLI is old school, but now there's a web wallet at MyMonero.

Unlike XMR, Darkcoin is not intrinsically anonymous or unlinkable.  Darkcoin isn't intrinsically anything; it's just a brand name for a constantly mutating project with nothing under the hood but lofty goals and high hopes.

XMR uses ring signatures and stealth addresses in a brilliant cryptographically proven schema that secures privacy at the protocol level.

Darkcoin relies on features external to its dated Bitcoin/Peercoin-based protocol, such as Masternodes, in various attempts to build a privacy-producing Rube Goldberg machine, complete with shell games and other gimmicks.

XMR has never radically changed its privacy technology, and will probably never need to (especially once I2P, which provides for network-level privacy, is in integrated).

Darkcoin is locked in an eternal arms race with better blockchain analysis constantly threatening to unravel its secrets and reveal all previous transactions.

Every computer security expert knows 'security in obscurity' is a bad idea.  Apparently the Dark devs (and fanboys) didn't get that memo, as they continue to design ever more complicated mixers in a futile attempt to attain the level of perfect obfuscation XMR has enjoyed all along!