They're all trustworthy until they're not.

Maybe the oldest and biggest still going is Hydra, a Russian one. They're the cheeky chappies who recently proposed an ICO.

https://www.coindesk.com/russias-largest-darknet-market-is-hawking-an-ico-to-fund-global-expansion

r/darkmarkets used to be the place to keep abreast of them but that was shut down. This looks like the closest equivalent but a bit more general - https://www.reddit.com/r/darknet/

This too - https://www.darknetstats.com