I think Dark Matter is great too.. just waiting on my vendor flair.
I love the experience based incentive system. It reminds of you RPG games you used to play as a kid where you would gain XP and level up your character, except we are making real money and servicing the needs of customers.
A massive respect to the people capable of actually programming and running these markets whilst bringing ingenious flair to the features they've made available for vendors.
There are some truly brilliant minds out there.. if only I had access to such minds IRL. The learning and knowledge to be gained would be immeasurable!
DrugHub is also a fantastic market. The invisible hand of Adam Smith would be proud of how competition between markets has brought us so far within this obscure but special community.