There are so many Fude (Bamboo Brushes) to choose from.
For a beginner Japanese calligrapher, I recommend you find a minimum of two brushes to start with. One large brush and one small brush. Kengo 兼毫 style brushes would be a good one to start with.
There are many materials to create bamboo brushes. All natural, non synthetic ones are the best. For example, sheep fur, horse hair, weasel hair (sometimes called wolf hair), and others are examples of natural materials.
Kengo 兼毫 brush means both hard and soft. It’s not too soft nor too hard, thus it’s easy to work with for beginners to intermediate level learners.
For the handle, natural bamboo is light weight and good. There are two kind of shapes for the handle, one has wider round part at the end (Daruma-Fude), another one is straight bamboo stick. For small handed people, it’s easier to handle with the Daruma-Fude, because the handle is narrower.
What is the good brush?
Good brushes have good points on the top of the brush, and it bounces back to straight after you press down on it.
Prices of a brushes range widely. Some cheap brushes work enough for beginners, but there are some brushes that have too bad quality that it’s not worth it for you to buy. You should ask your teacher for advice on brushes.
You need different brushes to adjust to what you do
It’s same with any fine art, kinds of brushes are very important to perform well on what you want to achieve. It’s definitely better to use good matching brushes for your content and personal style.