I'm looking to upgrade to more epic gear, and PVP gear is a nice parallel means of doing so while sitting on Nightmare lockouts. However, PVP gear is throttled by a limited acquisition currency: Black Marks of Venice. I know that I can get these by capturing a facility in Fusang every half hour, or by winning in El Dorado or Stonehenge.
What I don't know is which of these three gives me the most black marks per unit of time. For the sake of determining what's most efficient for me, (since I understand mileage may vary based on a variety of factors), you can assume that I'm bad at pvp and uninterested in improving much, and that I am playing on a faction/server where I can reliably count on 'my team' to win most PVP matches thanks to population imbalance in our favor. Thus, solutions that maximize the reward for group success as opposed to individual contribution to that success are ideal.
Best Answer
When I was farming these I entered the Fusang Projects PvP battleground every 30 minutes to complete the quest 'Capture Facility' - which grants 7 black marks per completion. This quest has a 30 minute cooldown on it, and you can see the current status of the battleground before you enter it.
The most efficient method to this is ensure you're already in the battleground just before the quest expires so you can already be on your way to re-capturing a base.
As you mention it is also possible to get black marks from the Stonehenge battleground, which you can sign up for while waiting for your 30 minute cooldown to expire on 'Capture Facility'.
I personally recommend the repeated farming of Capture Facility every 30 minutes, as you will gain black marks in a more consistent manner due to the fact you are pretty much guaranteed a facility capture after your faction has lost the facility but you're not always guaranteed a win in the other two battlegrounds.