Which one of these two are the strongest/most dangerous?
Both are equally strong, but the killer whale is a more intelligent creature and won't attack just about anything. Great White sharks, on the other hand, are extremely temperamental and are known to attack everything, including humans.
Killer whales are found in colonies, which is a proof of their social behaviour and therefore, intelligence. Great Whites, like all other sharks, are solitary hunters.
Their hunting skills, of course, are equally impressive and they are both equally important ecologically.
Also which one would you prefer to see in real life in a wild environment?
I would prefer a killer whale, like I said, sharks are temperamental.
who would win in a fight between the Great White Shark and the Killer Whale?
This is a difficult one, pretty much depends on the size of the animals which are fighting. They can both be equally fierce and are equally strong. But since killer whales are always in groups, an attack on one member of the group will result in the entire group retaliating fiercely. So only a foolhardy shark will take on a group of killer whales
Never argue with idiots. They will bring you down to their level, and beat you with experience.