For me:

• Card/CalDAV baikal : so that I can sync my calendar and address book across phone, tablet, workstation, and laptop
• Messaging prosody/synapse : private chatting with family.
• File sync Nextcloud : for access to various files. This is the only one that has worked consistently for me. Syncthing et al would constantly lose connection and the file I needed wouldn't be there. Works fantastic for syncing Joplin notes.
• VPN wireguard : to access things remotely and securely
• Audiobooks audiobooksheld : I have a ridiculously large audio book library and enjoy listening to them when driving. This way I don't have to preload my phone.
• Ebooks calibreweb : another large library. I have separate instances for different types: Magazines, regular books, RPG/gamebooks.
• Version control forgejo : for coding and creative writing projects.
• bookmarks shaarli : I find myself using this less and less. I use Firefox's built-in sync, so I'm thinking about switching to separating selfhosting that instead of shaarli.
• Photos Synology : looking forward to immich getting stable. Once they get past regular breathing changes I'll move over to that.

I have stopped using most of the services that got me into selfhosting. Things like rss and wikis. I try new things from time to time but kill them if I don't find myself using them regularly or if the maintenance cost is more than the value add.