For me, first of all, it's the talent. That is the magical thing.
There is no impact/stage presence if you see a band/musician walking up on stage that you never heard of, no matter how good-looking they are.
For instance, Nirvana's attire are not much with good clothing, but, you judge now how their music became a legend.
They have a huge impact, figuratively and literally.
Not also Nirvana, but other musicians that became legends. They may be not very good-looking but they are really a rockstars because of their talents and ability to communicate/express themselves with the audience. That's my observation.
I agree with aura and attitudes. They really affect stage presence. Looks and clothing are least.