I recommend the Fillimilli powder brush.

I used to only use brushes for applying eyeshadow, but after using Fillimilli products, I started buying and trying out various others. I found that my regular powder puff was just too lacking, especially when applying powder in the summer; the application feel and overall satisfaction were insufficient. So, I bought a brush from a brand I've always loved, and now that I just swipe it on, it applies evenly without leaving any streaks on my existing makeup. I am extremely satisfied.