Prime Hiruzen surly is the most powerful. It's funny people deny that a prime hiruzen was the strongest of the hokage's but the playing field was pretty much in the favor of the two reanimated kages. It was said that the two reanimated kage's where not at full chakara well... What about hiruzen at his age? Also people try to say that he wouldn't have caught the two kage's in the reaper death jutsu if they where at full power... Well Hiruzen sarutobi said himself when he was fighting Hashirama that he was just as strong and as fast as ever. Stating that although they were not perfected zombies they where at top condition as far as speed and stamina. It's also said by many Hashirama tobirama madara fan boys that the hokage's barely used any jutsu while fighting sarutobi... Well neither did Hurizen. It was stated that he could barely make clones because of his age and chakara. So how do you know Hiruzen didn't have better Jutsu 20 years ago. Keep in mind 20 years ago he would have been 50.... Come to think of it the first hokage used a hidden jutsu deep forrest.... One of the jutsu's that gave Madara and the 9 tailed fox trouble but Hiruzen still beat it. It's also said that the power of hashirama is myth like... If that is so than should have been able to beat an aged Hiruzen with only half of his strength.