My favorite way to farm moonstones now:
take your high level dude through the claptrap DLC in normal mode, and then go kill eclipse/eos as many times as you need moonstones. Then splitscreen in another character and have that guy at concordia so you can join in with your moonstone farmer and spend moonstones on upgrades or grinds. Go back out, and farm moonstones again.
As for XP and infinite kills, Vorago’s Guardian Hunter quest definitely tops the cake. The neat thing though is that there are a couple other quests where you can keep killing nonstop. The turret training one is annoying so I usually don’t do that very long. There’s the research and development map where that crazy lady scientist who loves science and brains sends you off to “crit em to get the brain”. I go where the boss stalker spawns, “X-STLK-23” and pummel those guys on their two spawn points. Considering that they spawn on two places this xp farm would best be done with a buddy. The added bonus is getting to kill some stalkers there too.
I’ve found other parts of the game with infinite spawning as well. Guardian Hunter is just the most convenient.
Thanks for the reminder tip about badass challenge farming. I’ll go back to normal mode and p0wn a bunch of those challenges until I can do a badass prestige reset. I still haven’t done one in TPS yet. That’s what I get for playing all 6 characters to max level!