While reading through Hiruzen's page, I stumbled on a very peculiar phrase: Hiruzen was considered the greater kage at his time, and the greater shinobi of all Konoha history. Curious, they however clearly stated that Hiruzen was stronger than Hashirama.
During part one, he hold his own against Orochimaru and the reincarnated first two kages, despite his former student stating that he was way more weaker and had poorer chakra reserves. But that's not all.
Hiruzen was appointed to be the next kage at a vzry young age, being called a prodigy like his father was, hailed as the God of Shinobi. He learned to use the five elemental releases and could use them with the same proficiency. In Konoha, he was renowed as the teacher, knowing everything on the village techniques, even special hiden jutsu from clans.
Prime Hiruzen is then considered the strongest kage in existence, so we could say with confidence that:
Prime Hiruzen >>> Edo Hashirama + Edo Tobirama + Orochimaru
