The pros squeaky brakes

[The Spanky]

Typically, pads with higher metallic content are more prone to squealing, especially when hot. Organic pads pretty much don't squeal, but they're a rarity nowadays, and I'm not even sure you can even get organics for bikes anymore, because they wear fast and overheat easily. 

Semi-metallics tend to be the noisiest. Ceramics are less noisy but also have less stopping power than metallics.