I'm only in 5 worlds. Looking at it from one owner's perspective, 1-6-17-30-49, that seems really close to how I feel about the competitiveness of each world. As a disclaimer, I'm just starting my 2nd season in BTP(49) so that's a very lmited view. And, quite honestly, my viewpoint comes less from looking at the good teams and more from looking at the bad ones. Every world has good/bad teams. Good worlds limit how good the good teams get. There are no unbeatable powerhouses in any of my worlds. But the bad teams determine the quality of the world to me. When the top teams rest 3-4 starters against a team, they're saying "They are not competitive."
One way I'd look at it is Runs Allowed vs. League Average. I'd take the bottom 25% in wins(8 teams) and compare. Here's how my worlds come out(last full season except MG which is at game 162):
Coop 699-706 7
MG 715-756 41
Mantle 739-823 84
Hamilton 729-797 68
BTP 766-885 119
Hamilton actually comes out better than Mantle which surprises just a little. 8 teams is pretty substantial and covers the "park factors" along with the random total turd team(which really hurts the world).