TPTB_need_war, what about ShadowCash?
Just a (arguably plagiarized) copy of Cryptonote technology, so same conclusions as for Monero.
https://z.cash/ is the only potential solution for making metadata correlation irrelevant, but all I know about it is here:
http://zerocash-project.org/ It requires "Genesis Keys" to be created at the origin block. If someone held all these keys, they could basically utterly destroy/manipulate the currency. There can be one key (really bad and unlikely) or even a hundred keys (more likely) - but the fact remains that if one entity ever held all these keys, the could destroy the currency. That is an unacceptable risk.
Also, it is
too opaque. If someone discovered a coin generation bug, no one would know until the market was endlessly flooded with counterfeit coins - the blockchain is too 'dark'.
Cryptonote coins really are the best solution: Monero, Aeon, and possibly Boolberry if they can work the kinks out.
Shadowcash doesn't suffer from that Zerocash flaw, but it has been built in such a way that if Zerocash ever comes to fruition then it will be able to slot strait into the Shadowcash framework.
It currently has all the advantages of Cryptonote coins with the added advantages of being able to freshly mint your own coins by converting SDT into SDC (brand new coins with no tx history just like mining them) and it is built on the bitcoin code base which enables compatibility with bitcoin going forward as well as faster development.