My money’s on the bear
Let’s put aside the inherent racism of this question for just a second; but let’s also not kid ourselves that it isn’t there.
Obviously the answer is bear. Bears can perform both in and out of water and have 2 weapons at their disposal; teeth and claws. Sharks have only claws.
Bears also have a much shorter pivot radius and can follow through with a second attack that much faster. A shark needs to set up each individual attack.
Bears can also use tools, are known to ride bikes (see here: http://➡.ws/⇔迍) and, in some cases, are Russian. I fear Russians more than I fear sharks. So the bear/Russian venn diagram has a much more serious fear overlap than the shark/Russian venn diagram. Another point for the bear.
Caveat: Of course this doesn’t apply to pandas. Pandas are pussies and without the care of very cute very tiny Japanese girls who keep them alive with the magical power of cell phone pendants would be doomed to extinction.