A lot of people say it's because he's Marvel's Batman (which isn't true, that's Moon Knight) but...holy shyt, if Batman had like a fifth of the resolve T'challa has, shyt would get /done/
BP's not some fukkass revenge filled hero or some crazed/power mad scientist, this dude is a fukking /king./ King of arguably the most technologically advanced nation on earth (African nation not fukked with any westerners, resource location for the strongest metal in Marvel canon, Vibranium) BP's incredibly intelligent. Multilingual, proficient in multiple martial arts, etc.
Dude has like the majority of the Marvel verse shook in his presence. he 'fukks' with the avengers, but he don't really 'fukks' with them like they think they do. He has Stark shook, Thor shook, beat the shyt out of hulk a couple of times. Only dude he's really cool with out of that group is like, Rogers (and to a lesser extent Spider-Man.)
He doesn't work on some plain 'good/evil' morality line, instead he does shyt that benefits his people instead of the world. there've been times that people had to 'beg' for his help, and he sits in his outfit (which isn't really a costume--ceremonial garb) just looking down at people.
I could go on and on and on, but...motherfukking T'Challa
.
this BP movie is gonna make so many nikkas mad