I'm mostly interested in Navigational data and Geo-coding. I mostly use StreetComplete on the go.
I host a mirror for OrganicMaps, which is imo the best experience for new users or users who just want to navigate and search places on-the-go:
https://omaps.webfreak.org/
On desktop / on the web I think Qwant Maps is the best experience for these users. (It's open source, which is great, but it looks kind of difficult to contribute things to, as PRs are open for months without reply and they have an internal git where they do different stuff before it gets pushed)
Mapcarta looks cool, but it's a bit too much information and I would prefer if this kind of service would be open source to fix minor annoyances. Would love to have this website, which combines different sources of Open Data, in Qwant Maps.