My small arsenal includes:
116- Small Blush brush. I use this for StudioFix & powders. It can also be used for cream products.
129- Blush brush. My fave of the blush brushes. Soft diffused application, never streaky or racing-stripe.
168-Contour brush. Great for defining the cheekbones, but can be too streaky.
190- Foundation brush. A must.
217- Eye Blending brush. This does it all, from all over washes to highlights & crease blending. Can be used with Paints & cream products as well.
219- Eye Pencil brush. Excellent for defining the crease, lashlines, & creating smoky smudges. Also makes a decent concealer brush in a pinch!
My next purchases will be the 187 (very versatile), 209 (for use with Fluidlines), 224 (the most popular crease brush) & the 316 lip brush.
Now is a good time to pick up one of the Pattermaker brush sets at Nordstrom:
#1 - 239, 219, 266, 316, 129
#2 - 190, 212, 252, 194, 168
Five brushes for $47! I'd recommend #1.