1.Foundation buffer brush: You should go for a good foundation buffer brush if you use mouse or powder foundation.For liquid one you can go for sponges.
2.Blush brush: Brush blush can be used not only for powder blushers,but also for face powder,bronzer and contouring.
3.Eye shadow brush:An eye shadow brush is a must have.You can even use it to apply your lipstick evenly.
4.Concealer brush: Concealer brush can be used as eye shadow brush as well.But it is not recommended to do so specially if you have acne or problematic skin.You should clean the brush or sanitize it before each use.