A problem with zcash is that most people only use transparent addresses, so if you are one of the few people who uses shielded transactions, you’re wallet is already marked as “dirty”. In addition,I don’t know if any other crypto has tor nodes and dandelion++, zano and pirate chain included. Add to this private transaction rates and a large anonymity set and a skeptical community that actively searches for and rewards finding flaws, there is no competition. That may change in the future, but not any time soon.