I use this brush.

It's an eyeshadow brush. I mainly use it for the lower lash line or for applying eyeshadow broadly. I bought it cheaply at Daiso. Some brushes shed bristles and feel rough, which isn't great, but this one is soft and doesn't shed. It was quite good for the price. There are surprisingly many things to buy in the beauty accessories section at Daiso, and this brush was a good choice.