The Scipii is the strongest faction in the entire game
They get all the advantages of the other Roman families, plus they have the best military temple with weapon and armor upgrades, which are significantly stronger than experience the Brutii get from their temple.
The starting position is excellent, allowing you to expand in any direction you want. Conquering all of Greece is easy, the Brutii don't have enough time to capture even Apollonia, and the Julii can be blocked by taking Caralis, Mediolanium, Patavium, and Massilia. Syracuse is a great contender for being the city of choice to rush for the Marian Reforms since it has grain, can trade with Carthage (which also has the grain resource), and peasants can easily migrate from Messana and Lilybaeum, boosting the population numbers.
The two other temples are also great, law is the best way to keep public order and corruption under control, and the unique boats, while unnecessary, are a nice little bonus.
Of course the entire game can be finished with just Hastati/Militia Hoplites, even on VH, and the difference between the Roman factions is mostly negligible, but the Scipii still have an edge. Especially if you play mods like Mundus Magnus with huge maps, and deliberately let the AI grow more powerful by expanding at a slower pace.