Each type of bristle has different characteristics and a wide range of choices in terms of quality, size, density, and shape. I've had brushes I would rate from great to disgraceful in badger, boar, and synthetic. (I've never owned a horse-hair brush.) I mostly use synthetics for their ease of use: you don't need to soak them and they dry quickly. Nowadays, you can buy a very good one for under $15. I like a boar to face lather, and once they're broken in, they get nice and soft and do not smell like a barnyard. And when I want to live large, I'll give a high-quality badger a go. The lush feeling, for me, is the height of luxury.