Statistics show that the Hippo kills the most people in Africa every year with exception to the mosquito. I don't believe that these statistics are very accurate as the Crocodile also takes many lives every year.
The Hippo is 99.99% a herbivore so after killing a person they just leave the body and go back into the water. A Crocodile will normally eat whatever it kills.
Here are two examples:
David goes down to the river to do some washing and in the process he gets killed by a Hippo. The evidence is very clear that a Hippo killed him as the hippo’s footprints may be visible and the bite marks on David’s body are also clear, so another death is marked off for that year.
David goes down to river to do some washing in doing so gets killed and eaten by a Crocodile. No one saw what happened, all they know is that he is missing.
So it is impossible to say who kills more people, it could be either Hippo or Crocodile. I think it’s the Crocodile.