Both great projects I would also put librephotos to the equation with its feature rich unofficial android client Uhuru photos
All have great android apps and great Dev base
Have tried all three and also tried every other selfhosted image gallery
Photoprim is overall the most mature and complete in features
Yes it requires a third party app to sync your assets but the auto index feature if you sync to their webdav endpoint is killer. This means the proccess from the moment of taking a picture till it shows up in your photoprism gallery is “instant”
Also the unofficial android client is super great and almost android TV compatible
So
To be honest there is not a fair answer You really have to hey them all
:-)
Most seem to mention privacy. Choice as important as privacy. Do things your own way. Selecting the services you want to do common things on your device. As I went along I realised how deep google enforcement was and how hard they made choice for users. That made me want to rip off even more google from the device. I came to a state that I host every service I run my self.