Recruits
For recruits per energy.
But people farm non 1.8-7 stages for many reasons.
My preferred stages are 1.7-4 for filling Wanted Monster mission chest ( Monsters, Rugged clothes and string ) and 1.7-7 for farming for Rugged clothes. I have 7525x Common Herb so 1.8-7 not that exciting.
I love Recruits I and Recruits II for recruits per auto play hour. Not as fast as loot tickets, but still a lot of recruits fast.
Worst Energy Per Loot
I think my least favorite quest stage is last stage of Common Battle items ( skip ). If I Recall Correctly it is 12 World energy for some Arrow Attacks. But most of the last stages of most Common quests are pretty bad.
As far as I can tell, the Devs put a lot of though into ascension items and hero XP, then ran out of ideas for stages. Season 2 is much more interesting.