In water, Hippopotamus. On land, Rhinoceros.
Hippos are crazy territorial, so my money would be on them. It’s hard to imagine a rhino losing the battle, but the pure unfiltered rage of a hippopotamus when you trespass his territory will frighten even the boldest of rhinos.
I’m surprised everyone is betting on hippos.
Rhinos are bigger (generally), heavier, move faster, have collagen armor, and have a horn.
Rhino’s have low intelligence, can’t swim (well), hace poor eyesight, and are smaller. My money’s on the Hippo.