I picked up a Winsor & Newton Monarch Mongoose size 4 filbert at a local art store, and after using it a couple times I decided to order about 10 more from Dick Blick. I was a little hesitant to spend so much of my order on paint brushes, but every time I use one of these I just love it! I've never had a brush hold it's shape so well, and they are both firm and flexible at the same time.
I love, love, love these brushes. Seriously.