W&N7, Cheap Joe's Dragon's Tongue line, and Escoda are the brushes I use the most. My 1 and 2 from Cheap Joe's are awesome. they're a natural sable (of course), and have the same spring and length of my Series 7, but they don't puff out as much in the body. I like my Series 7, but my Dragon's Tongue gets to be my workhorse because I sometimes feel that the Series 7 holds too much paint.
Of course, there's no real difference in cost to me. I'll but whichever one is the better sale price in the catalogie when I need to replace it. Sometimes the Series 7 is at a better price, sometimes the Dragon's Tongue.
My Escoda 0 has been getting used for close to 3 years now. I had to cut down the handle (why they felt a 0 needed a 8+" handle is beyond me), but I've been very happy with it.
I tried a 2 from Isabey. I'd heard good things, and the price was about the same. I actually had two of them. Both of them constantly lost bristles, and they are now smaller than my 0, and are just ratty. I'll never buy an Isabey brush again.
Dick Blick is a great place to pic up brushes, but I always check Cheap Joe's Art Supply first. Joe is an artist and started the company. most of the workers there are artists. And the lines of brushes they make for each medium are really great. As I said above, I'll put my Dragon's Tongue up against my Series 7 any day.