After reading some of dreagod post I had to do this. People on the base seem to like comparing people to itachi for some reason and I think they underrated him a lot. First of itachi is arguably the best genjutsu user we have seen in the series and jirayai is a person who genjutsu skills are average at best. Next itachi is faster than jirayai. He's faster at moving during battle and his speed with his handseals are definitely faster than anyone else has been shown. Finally people think sage mode is what really put jman over the top and I agree. I myself think sage mode is underrated on this base, but in all honesty from what we seen against pain it takes him awhile to summon the sage toads. Now without sage mode I don't see jman standing a chance against itachi but with it and his summons I think jirayai is overral stronger.