I am thinking as the gentleman's stated the key components are ability to finish engagement and ability to endure the fight.
For me, I believe the gorilla's strength and how it can fight using hands and arms overcomes teeth and only swiping abilities of a bear and lion or tiger. The gorilla can pound the sh*t out of either the other two while they are attacking with essentially only biting as their main weapon where the gorilla can grab & bite. Then comes the ability back off & regroup if necessary, "finish engagement" then endure a lengthier fight. Tiger/Lion and bear I think would disengage and run if not getting the best of it's opponent where a gorilla would back off regroup and continue if the fight continued. But what the hell do I know other than I like lions but think a gorilla would kick both their asses. But in the end it's just an opinion. I think I'd have a better chance of surviving against a bear or lion than I would a gorilla, that bugger would crush me like a cheap thin plastic walmart water bottle.
Watched the vid after I made my choice.
A gorilla can pound the bear or the lion but remember they are used to having big animals smash them already. A 1500 lbs moose for the bear or the deadliest animal in Africa for the lion, a cape buffalo. They can lift a vehicle off the ground. Like John pointed out, a gorilla canno punch, just slap. Slaps hurt way less and do little damage. If they grabbed and tried to bite the lion or the bear is way better suited for battle.
One thing John said that is not true is Lions are sprinters. In a fight they would gas in minutes and would not last long in a sustained fight. Bears fat is armor, the lions claws and the gorilla could do significant damage to the body. The skin and fat are really thick. Bears are the biggest and they know how to use their weight (Look at humans fighting, a good wrestler can control even a dangerous BJJ guy and pound on them on the ground. Now think about a wrestler that is 2x as big as his opponent with 5 inch claws and a mouth and teeth that crush bone)
Yeah lions are built to fight but their downfall is their cardio.
Friggy, a lion would kill you for fun. Gorillas do not kill. I am sure there have been people killed by gorillas but in my cursory look google search I found none documented. I think they just do not have the heart for it. Now a chimp? Those things will kill and maim humans for sure. Griz bears normally attack humans to defend their cubs and will leave when they feel the threat is over. Many times the person is still alive if they play dead.
When I was a kid I went to a B day party with Deena the chimp/ She was a very young chimp and we took pics, polaroids. When she walked over and took my hand and drug me over to the birthday cake (not mine) nothing I could do. She would have drug me even if I was layed out and she was 40-50 lbs I was 90-100. She was so dense. Anyway, a gorilla is even stronger.
And for those that do not know, humans have a bite force that is pound for pound about WAY stronger than gorillas. A gorilla can bite at about 1300 psi, a human can bit at 1100 psi. Humans have a bite force close to double that of a chimp of equal side. We just do not have the equipment to do massive damage. Humans are in-between a hyena and a gorilla about equal with a polar bear. Thanks search engine.
Also gorillas have a very strong bite force because their food. Bamboo and other tough plant matter.