I chose to compare PhotoPrism, LibrePhotos, and Damselfly, because they seemed like the strongest freely available candidates for a large library of photographs.
I am mostly interested in face clustering (DBSCAN) and other "AI" capabilities like auto-categorization. Import speed is not as important to me as "playback" speed. I don't mind if it takes a few days but once everything is indexed and processed then it should be fast to explore everything.
The dataset that I used for this comparison was under 22GiB but over 750,000 images. Mostly AVIF files but some PNG and some JPEG.