Simply put, tsunade, jiraiya and orochimaru all have their own advantages and depending on how they use their special techniques will determine who will in the end, have the higher chance of beating the other.
In my opinion i believe that they each deserved their legendary sannin titles. Whether or not we agree, they recieved that title and we should accept them all to be equal. We can't be partially following the story. No such thing as agreeing with part of the manga and disagreeing with the other part, and for this reason i have to accept that all three sannin are equally powerful.
Tsunade's medical jutsu and taijutsu goes beyond orochimaru's and jiraiya's.
orochimaru really isn't that strong. He is weakened by his hunger for power. Jiraiya is the only balanced one out of them all which is why i probably love him the most.
Tsunade is the strongest female in Naruto... that alone should give her props.
besides, who doesn't like Tsunade?