I've been playing a handful of STO Foundry missions (both KDF and Federation factions) in the past week. I'm moreso drawn to missions with a quality story than pew-pew action.
Among them, there's one mission I've really, really enjoyed:
Achaemia: Episode One by Zadama
If you enjoy story arcs, like Drogyn1701's "Dissent" series or SBCouto's Klingon missions, then you'll appreciate and enjoy this one. There are nods to TNG, the Star Trek Vanguard book series and even another sci-fi property... but the mission remains original. And Zadama does a terrific job setting up the next mission, too.
Foundry Mission Title: Achaemia: Episode One (ST-HCKSPY9Z2)
Minimum: Any Level
Estimated Mission Length: 30 Minutes
When an archaeological survey ship discovers an expanse of Tkon ruins deep within the Arucanis Arm, close to the end of its tour of duty, your ship is dispatched to resupply and assist them.
Sometimes, however, history is better left untouched.
Content: A text heavy mission with limited combat. If that is an automatic turn off, you have been warned!