Alright... posted something.
(235078.1)I think that country ranking is the best way to determine team toughness. Sure it weighs the cup more than league play, but the cup is the only place where inter-league play happens.
But please also, don't take the league ratings too seriously. Like I said, they're very subjective. And just because a league isn't terribly tough, there can still be hard-fought battles for the top positions with great teams on both sides. Also, league toughness can vary a lot from season to season. Some leagues get as many as 6-7 new managers in a season. That can change a lot quickly.