DietPi. I have quite a few VMs running DietPi, very light, simple, "just works"!
I have to reluctantly use Docker which is cumbersome, awkward and confusing in comparison. A DietPi VM is simple and easy to run, use and more importantly, keep backed up. I really hate being forced to use Docker when DietPi exists and works!
Well it won't. You either tell it to assume that say oldest is always source and if there are identical files then you get asked to choose.