We are still very early in tour 138 and the ultra-cheap Tiger II for the first few days created an abnormal situation as well, so I would wait at least one, better two weeks to let the numbers settle down.
That being said, there is no doubt that the M4(76) is still the best choice in terms of combat efficiency and will continue to dominate the AH battlefield, especially in offensive operations where few players are willing to throw 15-100 perks away for a "true" perked tank.