For me, I'd say either Metallica, Notorious B.I.G , Green Day, or Purple Haze.

6655585
B. I. G or Green Day

Notice how all of the ones you said are from Vento Aureo.

Za Warudo

For me it would be Death 13.

Za Warudo Ova Heavon!

Aqua Necklace

Now that I'm looking back on this with some further knowledge of other Stands... I'd have to say the scariest one for me now would be... Limp Bizkit.

for me, it comes down to 2 different ones.

Tusk ACT 4.
it holds the power of INFINTY.

Golden Experience Requiem.
but, then again, even infinity has a point it can be reset to.

6655585
Either Death 13 or Justice for me

Honestly C-Moon. Not only does it look and sound terrifying to me, but it’s power is super deadly. One punch can turn someone inside out and it can switch gravity, killing anyone within miles away from it.