Zerocash is deeply flawed on a fundamental level.  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.