[NTG-context] What is the prefered way to load a system font ?

Hi again, I'm puzzled about the prefered way to load a system font, and I read the wiki is outdated. Is \setmainfont deprecated for \definefontfamily + \setupbodyfont ? Or are they different things ? Also, how am I supposed to find the right family name to feed both with ? I read somewhere that the output of mtxrun (which column ?) should be used and not fc-list output, then I read the opposite, and I read that the --info option of mtxrun should provide the same family name as listed with most GUI software, yet I tried and it doesn't… Thanks. Regards, Goulven.