The writing brushes in the Tang Dynasty were made of purple hair, which is rabbit hair. Nowadays, the craftsmanship of making brushes is far from that of the ancients, and there are very few good brushes.
Purple hair is a hard hair, so it is recommended to use langhao or jianhao.
As long as you use it smoothly, it is a good pen.
A good calligrapher does not choose paper and pen, and can write well with any pen.