Jiraiya: The Most Powerful Sannin
While none should argue against this man's prowess, there are still many who truly doubt him enough to not place him in "Top 10s" or even overlook him as perhaps a top-5 ninja. Here I will try to persuade you to believe that Jiraiya is in fact an absolute beast and eats up the comp any day.
Taijutsu - While Jiraya wasn't exactly a hand-to-hand combatant, he could still go toe-to-toe with some of the greats. He is far from a Gai or perhaps Lee lvl of Tai, but he has been shown to hold his own. He was able to counter/stop attacks from the Giant Multi-headed Dog summon while gathering Sage chakra and he was able to toss a giant-sized snake a great distance w/o the help of Sage mode. While in Sage mode, his Tai was increased to deadly effect. He was strong enough to completely cave in the eyes of the Human Path with a simple kick and launching the body a good distance at the same time. He was able to launch an attack from a high vantage point before his sandals even hit the ground (which fell first).
Genjutsu - It is true that this isn't his best area, however, he still had enough profficiency to know the counters of genjutsu and while in Sage mode (with the help of the 2 Sage frogs) a sound based genjutsu could be used to devestate the strongest of opponents. Now, you will say "wait, that was technically the frogs' tech". Well, that is true, but in a sense since they were apart of his Sage mode, then he could arguably be accredited with the tech. This is debatable though.
Ninjutsu - Now this is hit creme-de-la-creme. Jiraiya was a master of ninjutsu. Putting to use an impressive offense of Earth and Fire to both trap and char his opponents with ease. His Transparent Escape Tech made him an impressive spy and aided him in his efforts against Akatsuki AND Orochimaru without the latter knowing he was on to them. He was a master at Barrier jutsu as well. He could release a barrier to find a camoflouged enemy, as well as, trap an opponent inside the belly of a frog and use it to his advantage. He could even turn his hair into deadly weapons or as a powerful shield.
Toad Techs - Yes, he was called the Toad Sage for a reason. He could summon toads as large as Gamabunta and could summon the near-indestructible eso****us of a toad in which it will eat and dissolve his opponents with ease. The only survivors were Itachi and Kisame..largely thanks to Itachi's Amaterasu. He could also utilize their oil techs and use them for battle.
Fuinjutsu - This was also a strong suit for J-man. He could overwrite a crude seal (by a prodigy, nontheless) and restore Naruto's natural chakra flow back to normal. He also altered Naruto's seal to it could supress the Nine-tails even further, thus protecting Naruto. Finally, he could seal something like Amaterasu and by effect, extinguishing the un-extinguishing flame.
Senjutsu - Not much needs to be said here. He was a beast as a Sage. Still able to fight off Pain with 1 arm. G-status.
Legend status - Jiraiya was such a beast Kisame and Itachi [B]refused[B] to battle Jiraiya. Itachi himself noting that the best they could do would be a stalemate, even with reinforcements. Kisame noting that Jiraiya was "on a whole other level". Pain, one of the most powerful ninja ever even stated that J-man would've won if he knew his secret. Jiraiya's stamina was so strong, we was able to do battle with Orochimaru (though Oro couldn't use ninjustu) with only 30% of his strength. He even took an outcast and slow-learner Naruto and made him into the ninja he was today. Not only through his mere physical accomplishments can we call him powerful. He held the term "powerful" through his words, as well. The first book he ever wrote led to #1 Naruto becoming more and more like the Sage, in philosophy, everyday #2 In the resurrection of countless Konoha shinobi. His book truly made the Child of Prophecy and will lead Naruto to create a world of true peace. All in all, Jiraiya should be considered nothing less of a legend status just shy of the Sage himself.