After methodically watching every single Lisa Eldridge video this summer, I noticed that she almost always uses a traditional foundation brush. If The Great One herself uses it, there must be some merit. She favours the Boots No 7 one, and in her Chanel Confidential videos, she sticks with her Chanel one.
What I liked about this brush in particular was the thickness and density of the bristles. The last paddle foundation brush I owned was by EcoTools and it wasn't thick at all. Some people like that for the flexibility, but therein lies the magic of the Chanel foundation brush. The bristles are beautifully dense at the base of the brush, which gives the brush the stiffness it needs to push the product around your face. They taper gradually at the tip, and this thinner end is great feathering out any edges. The size is perfect for my face, and I don't see anyone having an issue with it. It fits comfortably around my nose and under my eyes, so I've been using it to blend in my concealer as well.
This doesn't drink up nearly as much product as other foundation brushes I've used, so be aware that however much foundation you apply to the brush is pretty close to how much will end up on your face. My favourite aspect of applying with this brush is that it makes it really easy to go back and add coverage -- with a kabuki or a buffing brush, I find that I end up with similar coverage everywhere, even if I don't necessarily need as much on one area.
Chanel's No. 6 Foundation brush is a synthetic brush that measures just over six inches and comes in a velvet pouch. In Canada, it costs $47 CAD, and is available at Chanel counters.