Comets and Panther are very similar. Comets have unnecessarily effective gun versus infantry. Comet need the same gun as Panther. Chosing commader/MG upgrade and if you pick commader upg., replace smoke with HEAT rounds (with MG upgrade, keep smoke).
They are not similiar , they are not even in the same league.
The Comet tank clearly overperforms in it's role being able to stand up to the Panther and in reality will beat it 50% of the time (considering the panther is supposed to be a premium heavy at ) there is really no reason why this should be happening. On top of all this the Comet also has fantastic anti-infantry power that the Panther lacks as well as insane speed and for an only slightly increased cost. The Comet simply has no weakness and no unit in the game should be able to claim this.