Intangibles are a thing and Kopitar has that in spades. When the Panthers make the playoffs let's see how it all unfolds.
Lastly, to say that Barkov will have a better career than Kopitar then a ton has to go right for him.
Intangibles are a thing, but not a very big one compared to what the player actually does on the ice.
Not sure about a ton, but sure, quite a bit has to go right for him. At least staying healthy and fulfilling his potential. I’m guessing both will happen. That is something you seem to be misunderstanding. This is 50% making a guess that he’ll have a better career, not 50% saying he will.
Also, the answer to the question depends on what is meant by better career. It could mean which one is considered to have been the better player, which one has achieved more team success, or some combination of both. If emphasis is on team success, I would say Kopitar. Winning cups is hard.
Edit. Typo