Just gave Syncthing a new look and I like it.
SyncTrayzor is a good version right now.
One Possible Setup:
If you have a PC that is always or often running then this may be a good setup. Currently I am using this to make files available that I want on all Systems. These are current files only. It is more a transfer folder.
The Collector-PC is also peered to the local main bookkeeping PC and receives a backup of that PC's backup. In other words the bookkeeping PC backs up to a second internal disk. Syncthing grabs those files and drops it on the Collector. The collector then has 2 Sync folders.
I do not sync documents, photos, etc. It is easy to access these files with Anydesk remotely.
Syncthing vs Resilio
Which is best?
It depends on how one would use them.
I use 5 different PCs regularly during the year in different locations. I do not want to keep any folders in sync. I want to use the software to transfer files quickly from one computer to another. Sometimes these files are large. Either program will do the job but Resilio is designed to run automatically and continuously. I don't need that.
I would remotely access the desktop, copy the file/files I want into the share folder and start the sync program. Then I would start the sync program on the receiving computer. Once the files are downloaded, I would move them to another folder, go back the the remote computer, delete the files from the share folder and turn off sync.
At this point it seems Syncthing is all I need. I would love to have Resilio's selective sync on the paid version but the cost seems too high for the added convenience. Other use cases may justify the cost.
If I had to actually keep folders in sync, i would use Resilio. Lower resource demand and no terminal window for two reasons.