For mining efficiency you need a proper route and not competing with others for sources. Yes you can get up to 8 with the proper equipment, BUT you also have to do a lot of clicking, a lot of moving, and sometimes a lot of downtime.
Herbalist allows less competition, you can do it in your own corner of the world, everything is right there in front of you, its easy to spam and do netflix at the same time.
Basically - efficiency will be based off how much attention you want to attribute towards the task. And, as someone else stated, doing dungeons really will be your best source of them.
So if I did Herbalist, I can plant the required materials to make Trans 160's anywhere in the world? If that's true, I might do herbalist.. I can't afford to get all that stuff required for mining, so that's out of the question :c
Edit: Can you also get Capnatcha in your Haven Bag? I was thinking about buying Garden gems and planting the required materials to make Transmutation 160's in my Haven bag.