I paid for Dropbox for a long time specifically because it was an independent option, but over time the feature bloat annoyed me more and more, and their dabbling in genai stuff was the last straw. Now I use syncthing over wireguard tunnels.
I've been trying to use it for a massive tree of ~250k files across ~500k folders, which only needs to live on one device at a time and sync to a backup in case it dies, and even if I tell it send-only/receive-only explicitly, it regularly seems to go cross-eyed at some change made in the folder structure and give up and rescan and hash everything, and if anything in the tree changes while that's happening, it gives up and just marks it a conflict to be manually resolved...or silently hangs until I restart it.
I separate my files in Syncthing into different shared folders that sync to different sets of machines, and put stuff that doesn't need syncing at all on my NAS. On paper this might sound more complicated but in practice for me it's a much lower mental burden.
The way I use it, it's a 1:1 replacement for the way I used Dropbox: a directory of files that are continuously synced across different machines, with a durable central copy that gets regular snapshotted backups. I understand that Dropbox has more features now, but that's pretty much all it was when I started using it; and the fact that Syncthing supports other use cases than mine doesn't mean it isn't a perfect fit for mine. Out of all my experience self-hosting ~replacements for consumer cloud services, it's probably been the most successful by far.