my thoughts exactly. any good player will be able to play a class well no matter how nerfed they are. if you play a class just because you want to be "good", then you're not going to enjoy it as much as if you played a class you truly enjoy.
You can go with the whole "doesn't matter, a good player will do well with any class!, and yes, a good player who plays a bad class can do better than a bad player with a good class.
Fact is however that regardless of how good the player is, with the current state of the classes a good player is always going to do significantly better with one of the stronger classes compared to the same player with one of the weaker classes.
I agree that in the end most people will probably end up having more fun with a class they like compared to a class they dislike, but lets not pretend that with the current state of classes that they would somehow be equal and the choice of class wouldn't matter in how well you do, and no amount of "skill" or whatever is going to change that.