White House Market is widely seen as the most secure. PGP is required and they only use Monero. There is no hot wallet, withdraws are processed once per day. It's harder to use than Empire was, but many people who take OPSEC seriously vouch for it. 68k active buyers, 1700 vendors
ToRReZ is a "community driven" market which accepts ZCash, Monero, Bitcoin, and Litecoin. They support multisig transactions, allowing users to avoid centralized market escrow. Multisig remains a difficult UX hurdle for most DNM users. 286 vendors, 13k customers, 200 days online.
Hydra is the darknet's longest running cryptomarket. Don't speak Russian? You're out of luck. Rather than smuggling product in the mail, Hydra vendors hide their wares in secret caches in Russian cities which buyers pick up. Hydra is working to launch an English version soon.