In a teleportation thread of mine over in GD a Army of Duplicate Datas was brought up by tracer . This got me thinking and this is the result .
You go either way . Hands on battle or full space battle( if so assume Data’s have Federation technology and Borg have Borg technology) .
I’d have to go with the Data’s because it’s already been shown that Data can kill a Borg in hand to hand combat ( the one where Lore was messing with his emotions ) and in a space battle although the Borg have vastly superior technology they lack the skill of thinking on their feet and improvising . Data has that skill in spades , and a army of Data’s would be a nightmare to out-think .
But the Borg are the Borg so maybe …