Digikam

Useful settings

Collections -> Ignored Directories -> #recycle

Metatdata -> Use Lazy Synchornization: makes you confirm the changes before writing them below. Useful when working on lots of pictures (eg face recognition)

Metadata -> Sidecars -> write and read on.

Miscellaneous -> Behaviour -> Scan for new items at startup, fast scan, detect faces in newly added images

Miscellaneous -> Behaviour -> Initially select the first item in the album

Faces

In the preview you can select show face tags on and off in the top left of the preview picture