Steady income and much less risky than running dungeons:
Follower Treasure Missions
I'm running 11 characters. All of them have level 3 Garrisons with these level 3 buildings:
- Tavern/Inn (to recruit Treasure Hunter followers - I currently have 5-8 treasure hunters on each toon and planning to increase this)
- War Mill (to get follower gear upgrade tokens)
- Barracks (extra 5 followers)
- Salvage Yard (because I'm doing mainly missions - let's squish a little bit more out of it) - vendoring almost everything.
BONUS: I'm in the process of getting Harrison Jones as a follower on all toons (you can level followers from 90 to 100 with 2-3 missions and he is a Treasure Hunter himself)
EXTRA BONUS: Garona as a Treasure Hunter will increase your chances on x3 reward from missions. I rerolled her traits 6 times to get it on my main. I'm not doing the legendary quest line on all alts, though.
Logging on twice a day, I'm getting 6-8k gold ONLY from Treasure missions. I'm not tracking Salvage Crates as much - but it's around 10k a week at least.
I use GarrisonButler to automate most of my Garrison stuff - including start the missions.
I stopped doing Auction House. 50k a week just from Garrison stuff is more than I need.