After some 600 hours in the game, I think it's "Scientific."
It just captures the lost possibilities of where South Underrail could perhaps be if the 'government' hadn't fallen. So many talented scientists working on innovative things, maybe with hope of absolving their conditions. But it wouldn't be.
Instead, labs like Hecate are now overrun with failed experiments, long paying for the sins of Biocorp. A mixture of high-tech, hope, and decay. You can even hear the buzzing of the broken power conduits. And it's cyclical and iterative, as things seem just get worse with each cycle in Underrail.
And the track works for so many locations.
As one person observes on the Youtube OST:
https://www.youtube.com/watch?v=ftWRSvRbUV01:03:25 Scientific is my favourite. So moving, emotional, mysterious, and heartbreaking. Just captures this game's loneliness with its intrigue perfectly.
and another...
"Scientific" sounds like something that could have been composed by the great Alexander Brandon (Best known for his work on the Unreal and Deus Ex soundtracks).
It's an A+ piece in an A album.