Why does Pi have two accounts of his ordeal? Which is the true story, and which one would you rather believe?

Pi finally gives in to the pressure of the men asking him about
the story of what happened because they don't want to believe his account with the animals.  For
Pi, in some ways he seems to feel that the account with the animal is far more acceptable, both
for himself and for others.  The image of the cook cannibalizing his mother and the other sailor
and then Pi eating him is so incredibly horrifying that the animal story seems to be far more
acceptable as a "true" account.

Pi gives the men the choice as to
which they want to believe or recount as the "true" story and they choose the one with the
animals as it is in some ways easier to "believe" than the one that is perhaps more
"true."