I also want to add that I think a great way of evaluating a leauge's competitiveness is how their champs do in the following years. III.1 holds up very well in this respect. . .so does III.5.
I agree with this methodology. I'm always curious about it. I know that my old III.13 league has had what looks to be 3 consecutive champs doing well in D2, this after several seasons of every champ failing in D2 immediately. This then indicates a trend that III.13 is getting tougher at the top, since teams need to be of a higher quality to promote.
I don't know much about any of the other III leagues. I do know that III.1's promotee this past season (LA Athletics) is in my D2 league (which was apparently the toughest D2 league ever historically last season),and that he's handled the transition to this tough league, with relative ease.
Seems to me that gives a lot of credit to III.1.