I think Kishimoto set the Three Legendary Sannins up like Janken or Rock,Scissor and Paper, where Jiraiya is weak against Orochimaru ( couldn't stop him from Leaving Konoha like Naruto to Sasuke) but is strong against Tsunade, while Tsunade is strong against Orochimaru and weak against Jiraiya.. basically Jiraiya is Rock, Orochimaru is Paper and Tsunade i Scissor..
and for the record ; it is stated that Itachi is stronger than Orochimaru but Orochimaru is strong against Jiraiya and that Itachi is not sure he teamed up with Kisame can take Jiraiya in a head-on fight...
So it basically sums down to technique-wise, Jiraiya's tech's works well against Itachi but not Orochimaru, and Itachi's tech's works well agaisnt Orochimaru but not so well against Jiraiya...
So Tsunade may not be able to take Jiraiya down, after my opinion
a little complicated but alas hope it clears things up a bit
Jiraiya is probably the best of the Legendary Sannins because of the fact he seems to be capable to stand up to Itachi wheras Orochimaru was afraid to fight him.Tsunade possesses superhuman strength and medical skills,but that is all she has.She would not attempt to use her signature technique because of its cost.Hence therefore i believe Jiraiya would win.
"You will only have eyes for Me!"
Jiriaiya would probly win because he knows more teckneeks for killing and knocking and opponet out.
ok i go for Tsunada all the way....she is so strong and she knows how to use her medical strength against her opponents like Kaboto...then there is that mark *wink*
~This felling, what is it..is this love?~
jiraiya all the way like they always mind over bronze jiraiya knows way to many tricks and skills to lose.