I gotta go with nunchuks. Anything you sling around on a chain seems silly to me. It seems like nunchuks are only good weapons against the unarmed. Anyone else has more range, usually something sharp in play and there isn’t a limp chain in the middle reducing the force of your strikes.
A quick dive back into the research says it’s still debated but generally the rough consensus is peasants having flails would have been super common, as they were a threshing tools. In Eastern Europe and Central Asia they were somewhat present as weapons, in Western and Central Europe they would have been pretty rare (and high to late medieval period) but not unheard of. They would have been the Nunchaku of their era. Like a French knight might think it an odd choice if a peer wielded one.
This article is interesting https://www.mdpi.com/2409-9252/4/1/9