i would not want to fight an animal in their own environment.
so i would absolutely not fight a shark. why? because it cant come on land, so it'd have to be in the water. and you are fucked in the water. it can drag you under, people are not mobile in the water, have limited visibility. you would absolutely lose to a shark if it really wanted to kill you.
a tiger in the jungle? terrible. you'd just be stalked and ass raped. those claws would murder you. there'd be nowhere you could go. you cant outrun a tiger, you can't outpower a tiger, and it would move like the wind with those kitty reflexes. i feel like i wouldnt even be able to touch it without being mangled or dismembered by those fangs.
a bear? hmmm. more powerful than a tiger, yes. but they're probably not quite as quick. i feel like if i needed to i could gouge a bears eyes out and stand a fighting chance. a tiger? i think making any move for its face would result in it biting my hand off. plus i cant see an environment playing much of an advantage to a bear.
so that said, i'd fight the bear.