*For everyone claiming Jiraiya would not be able to use SM against Killer B*
Do not be fooled by the prep-time in the anime, in the manga it did not last that long at all. With that being said, Jiraiya has the tools to go into Sage-Mode. (Transparent Escape + Shadow Clones) to escape from Bee and load his Sage-Mode safely in his Toad Gourd Prison. By all means, he has the tools to go into Sage-Mode. And yes, he did not use those in his battle with Pain (Even though they would be very convenient), but there are countless situations in Naruto where characters did not use techniques which would have come out the handiest...
Be also realistic here... You think Jiraiya, the Great Toad Sage, one of the Sannin, the initially chosen candidate for Hokage (twice), would be beaten in such a short time by someone like Bee?
Anyways, practically speaking? Sage-Mode Jiraiya beats Killer B.
But let us also use some admissions and statements, suggesting why Jiraiya is superior to Bee... Regardless of the conditions which made it difficult for Bee, Bee had a very hard time dealing with Kisame. While Kisame admitted in Part 1 that Jiraiya was on a whole other level than him...
Jiraiya would win with high difficulty (Considering the fact that he would have to use many techniques and act accordingly at all times, high intensity)