The Data-Book also says the Senju were the strongest during the Feudal Era. Probably b/c of Hashirama himself
Possibly. But weren't the Senju winning the conflict against the Uchiha when Hashi and Mads were children?
What I think gave the Senju the edge was their jutsus. Senju is supposed to mean 1000 skills or something of that nature.
Hashirama's Mokuton jutsus and the various applications.
Uzumaki Adamantine Chains and their powerful Fuinjutsus.
Chakra Enhanced Strength - Presumable created by Hashi and passed down to Tsuna
Edo Tensei, Kage Bushin, Multiplying Paper Bomb, Flying Thunder God were all created by Tobirama.
The Ninja Academy, ANBU, Military Police and Chunin Exams were also Tobirama's creations.
Tsunade adapted the medical corp, and had it medic ninja placed on all future squads during the 2nd Shinobi War.
Naruto created several rasengan variants with and without element natures.
With Uchiha, it's all fire style jutsus, shuriken jutsus and sharingan jutsus. However, as Naruto, Tobirama, Danzo, Minato, Kakashi, Guy, Kabuto and Oro all demonstrated, a clever person can learn the sharingan's weaknesses and develop strategies to combat an Uchiha.