I would agree with most people. I think drinking fountains, public toilets, shelters and just general shops (edit:with opening hours a bonus) are the most useful. Buses is also pretty cool info to have directly there. You can check Streetcomplete to diversify your contributions with ease as well, including adding wheelchair accessibility.
You could also take photos for !Panoramax@sopuli.xyz too? Then others can use your photos to add more stuff or just see the photos of your area.