Getting to my house. I got tired of people ending with a "you have arrived" more than a mile from my house so I went to open street maps and fixed it. (the automatically imported data for my street had the street name wrong - I'm guessing google imported the same data instead of actually driving the back road). While I was at it marked a few of the roads as requiring 4 wheel drive (legal roads, but only used by farmers going to the fields along it), thus preventing people from getting directed to a road they can't drive on.
I checked the "I consider my work public domain" box, 6 months latter google started giving better directions around my neighborhood. I doubt this is coincidence. However the ability to fix directions to your personal house is something OSM does better than google today.
Display flexibility: I can pick a rendering that works best for what I want (e.g. optimized for high contrast or print, prioritizing/de-prioritizing specific types of paths, or public transport). If you consider derived maps, there is even more choice, e.g. I can get a topographic map based on it.
Usefulness while on foot. In well-mapped areas, OpenStreetMap has every little footpath between buildings, through parks and forests, ..., with information if it is publicly accessible or not. Google Maps is missing tons of them.
Offline functionality. (Google could change this, but I somehow don't see them allowing to download entire countries at once)
Another: dynamic updates - in case of emergencies and disasters OSM data has often been updated by volunteers faster than other sources to reflect the on ground situation. For current examples See:
Kurviger is a routing service for motorcyclists. Pick a point, select a direction, and a distance, and it'll generate a round trip that doesn't go on the same road twice, you can go direct, or sorta curvy, or very curvy roads. https://kurviger.de/en
You mean few small (relatively) communities did this for themselves, because it was obvious no one will think about them and in most cases ordinary user doesn't care much about their input. I am talking about an average map user, globally. If you want global coverage and relying on people to input data, then good luck. I do really like the idea and I wish with all my heart that people would be that generous with their time and effort but we have to face the truth - people don't care, people want a working and complete service. Unless there is some automation in place and free data exchange OSM will never be first choice for general public. Idea is beautiful, execution... Well, Tokyo city, population goes in millions, buildings and addresses not available farther than few blocks away from the train stations. You can see roads but roads in Japan have no meaning. And yes, I could input my house (just 10 minutes from station, blank point on map) but sad truth is, I am unable to input all of them and as you can see - people don't care. They just use Google Maps.
Means - if you have an address, road name or topography won't help you. Most roads don't have a name, anyways. Not sure about US but in EU it's pretty common that houses are bound to roads so the address encloses road name and house number on this road. In Japan it is different. City is divided in areas, which are divided into smaller areas, all the way down to the building. Even locals often don't know the layout and are unable to tell how to reach the house on next square just by looking at the address.
Such as?