Yang Haobi is characterized by softness and poor elasticity, which is suitable for writing seal script.
Langhao is flexible and suitable for writing official and regular script.
Double-stranded brush is a mixture of wolf hair and wool, so its elasticity is slightly worse than wool, and it is suitable for writing cursive script.
Writing that font is not the prescribed kind of pen, but also can be decided according to personal habits. When choosing a brush, you should pay attention to the bristle part. Your stomach should not be too bulging, but must be sharp (some inferior brushes are washed with water).
If you are a beginner, you can choose wolf brush or double brush (personally, the "small and big" brush is easier to use, and you can write in any font, which is economical)