I have the 180, 181 and 182 and I love them all! First, the 182 is the best for blending/buffing out powders. It's so soft and it just feels good to the face! This leads me to the 181 brush, which is just a mini version of the 182. I wanted a buffer brush I can put it my purse or leave in my car and the 181 is just perfect for that!
Now, I just got the 180 brush and am planning to get another one. I can't rave enough about this brush! If I thought I loved my 187 and 182, I love love love this brush
! It's another one of those multi-purpose brush I think, which you can use for liquid foundation or powder.
Personally, I use the 180 to buff my SFF on my face, neck and decolletage. This brush makes blending so easy for liquid foundation so you don't worry about that demarcation line under your chin and on your neck! After that, I use the 182 for my beauty powder.
IMHO tho, if you can only buy one, I'll recommend the 180. This can be used for both liquid and powder while the 182 gets too sticky when used with liquid foundation. HTHS and sorry for long post.