I noticed that I mar the loops, not when I'm creating the loop, but when I open/close it to attach it to another item.
So now I use 2 pairs of pliers. I still use my round-nose pliers to make my loops. Then I switch to non-serrated flat-nose pliers to open and close my loop. I'm using a pair of
bent chain-nose pliers, but you could use any flat, non-serrated pliers.