I definitely want a smallish blending type brush to apply transition color with but I'd love to hear what other brushes folks like for the rest of their eyeshadow application.
Also I want good brush for bronzer and a smallish brush for applying powder to my undereye area (unless you have other suggestions).
E25 for crease and E40 for blending. I also really like the E35 for a lighter application of a different color above my crease to blow out the crease color.
The only Sigma face brush I own is the F80 so I can't help there.
Really NOT impressed with their face brushes, FYI (I have a contour and a tapered hi light). The eye ones are more effective, IMO.
I have an E35 which is fine, and the pencil brush (for detail, inner corner, or eyeliner) is also fine. The 35 is good for blending out crease/above the crease stuff. It is my favorite when I use bright colors which need as much blending as possible.
Their eye shadow brushes are good too, the ones I have are a little large for me. I was just on their site, I might pick up the enhancing set, seems more like the size I want to do some more precise stuff.
I bought a set of Ecotools because I wanted some synthetic brushes, but I returned them. They just didn't work nearly as well as my other brushes.
Aside from Sigma and MAC, you may want to give Crown Brush or Morphe a shot. Both are supposed to be very good for the money. I have a couple Coastal Scents brushes and they are perfectly fine.