This, in its entirety.I still participate however i like to see both sides just troll each other. Ill give my two cents though.
First is that both sides do not understand the manga, yep that is what i said. Both sides do not understand the manga.
Hiruzen was said to be the strongest and this echoed from the manga to the DB. Reason why Hiruzen was the strongest has nothing to do with the raw power that hashirama commands. Hiruzen was trained by both the 2 previous hokage's. Both were senju and this clan was said to be a clan with 1000 skills (or something like that). Hashirama/Tobirama passed on these skills to Hiruzen and that is why even at such an old age he is the only ninja in the series so far to command maximum stats in the 3 ninja arts. Secondly Hashirama left thousands of scrolls for the next generation of hokage's, most likely technique's from his clan (1000 skills by hype). Hiruzen was got his name the professor for leaning/understand all the technique's in these scrolls, something that i doubt even hashirama/tobirama couldve done because they didnt live to the age hiruzen did, but also the sarutobi clan were said to grasp technique's fairly quickly.
With the understanding of these technique's that were left in his possession he was quickly able to note the weaknesses of hashirama's bringer of darkness technique. Apart from blinding the opponent, all the others sense are not effected therefore smell, hear, touch and taste are the weaknesses of this technique and hiruzen took advantage of his understanding of his teacher's technique, which allowed him to overcome the technique and seal his previous teacher's.
You hear the quote "Knowledge is power". That is what hiruzen has over the previous hokage. Ill even give you a manga page, which might allow you to understand what im saying
Just read what jiraiya is thinking about here;
That is basically why hiruzen is the strongest. It has not so much to do with raw power but years and years of knowledge which would allowed him to defeat either hokage's in a fight.
What dan said is rathe straight forward. I do know whether prime hiruzen can defeat ems madara or not, though i agree dan lived during prime hiruzen's time. What i do know is that hashirama is the best counter for ems madara so much that it makes sense why danosaid what he did. It would be extremely hard for anybody else to defeat madara without having counters for his abilities.
Example hashirama's bringer of darkness trolls sharingan based genjutsu. If it blinds the user so to speak and the user only see's pitch black. They obviously arent getting any eye contact to use genjutsu.
Secondly is the ability to create mokuton clones and we know the clones troll genjutsu
Thirdly, hashirama is a kage bunshin user and its his scroll that naruto scroll in part 1. Clones troll genjutsu
Mokuton allows the user the ability to fight from all ranges. Short/mid/long. By fighting mid/long range hashirama further trolls sharingan genjutsu because its short range.
He must be a very good suiton user and by hype he has a large chakra reserve to counter madara's very high katon jutsu's by himself.
He has the wood dragon, which as we know suppresses bijuu.
He is the husband of an uzumaki. Its very possible that mito thought hashirama uzumaki technique's just like how kushina thought minato. Its possible that its a similar contract technique that hashirama used to undo the genjutsu casted on the fox like what minato did to obito
Its possible that with the wood dragon he can also surpress chakra and not just bijuu chakra and this can cause madara trouble and perhaps limit his use of susano. Yamato has shown the ability to control to an extent kisame's chakra. Its possible that hashirama can do the same therefore further limiting madara.
Finally. Whilst Hiruzen is the strongest hokage due to him most likely being the most skilful/versatile overall because of experience with ninjutsu and other forms of ninja art, but more importantly because of the knowledge he has on the previous hokage's.
Hashirama is stronger than hiruzen if we were to pit them up against high level opponents i can see hashirama winning more fights than hiruzen, though its just hype. However if we were to revert this and put them back in their hokage position, hiruzen is above hashirama. Hashirama would have trouble facing his former student than any other random high level ninja