Also there is a good article in the articles section about brush care and selection. Or maybe it's just buying a good one? Can't remember.
Thing is if you ask people here you're likely going to get their personal favorite (I am a Raphael 8404 man all the way!) but the characteristics of each different brush as they apply to YOU will be what is important.
I would also look at what people have to say about rosemary and co. brushes as well.
My advice, for what it's worth, is to by ANY of the top end brands and go from there. If you're stepping up from synthetic brushes I think you'll initially b eblown away by the difference the quality sable makes and from their you can decide if you need a firmer brush, longer bristle or whatever. But no matter what I think you'll be pretty happy with any of them if they're your first.