alt Hacker NewsI had been using mapcomplete to add images of artwork, which in turn used panoramax. However I saw someone else use Wikimedia Commons, and to me that makes more sense. Wikimedia ties into more systems, so if you wanted to create a Wikipedia page about an artist, there will be readily available images to use.
On the flip side, panoramax can be used as an open source StreetView. Different sites for different purposes I suppose
Wikimedia Commons also requires more up-front work by the uploader to categorize the image properly, which can be daunting if you're new to how things are organized there. But yeah, for well-known objects, adding Wikidata and Wikimedia Commons links can be awesome and there are plenty of apps making use of it to show additional information.