The Atago is, except possibly in armour profile, which I have no way of checking, strictly better than the Myouko. She has a better RoF (3.8 vs 5.0), better turret traverse (29.0 vs 45.0) and better torps (quad spreads vs triples). It also has a slightly better firing arc on the reverse facing turrets (probably 35°-40° vs about 45°) and a much better torpedo arc. Indeed most of its stats are slightly better the Mogami with the 203mm guns, although its probably worse than her with the 155mm's. She would be incredibly strong at tier 7 and as it is is pretty solid at tier 8.