I would assume the older washing machines with a big metal or plastic agitator in the drum would be much, much harder on clothes than modern front loading washers. Modern washers just toss the clothes around to agitate, rather than using a big hunk of material to do it. That being said, I think some modern washers run longer cycles than old ones, so it could be a toss up as to which causes the most wear.
I would assume the older washing machines with a big metal or plastic agitator in the drum would be much, much harder on clothes than modern front loading washers. Modern washers just toss the clothes around to agitate, rather than using a big hunk of material to do it. That being said, I think some modern washers run longer cycles than old ones, so it could be a toss up as to which causes the most wear.