The countback system is crude, but it has some merit in that it awards greater weight to a round where the player has held their nerve and finished strongly.
Delve into stats though, and it becomes highly objective. Is -9 a better score where the player has had a tap in every hole, or where the played has sprayed it all over the place and saved birdie with great putts? Is a 26 with every fairway hit a better one than a 26 with birdies saved despite being in the rough? I have no idea. In my mind a score is a score is a score.
Aside from the fairest possible way to settle events where the countback is identical, which is as a tie for first place (this is generally what happens on Tour when there is no way to fit in a playoff), I like the first posted score method. It gives an incentive for players to complete their RGs in a timely manner and not hold up the settlement by waiting until the last possible minute to play.