I've heard great things about Simms from everyone who owns them.
My opinion might not mean much since I'm very very new to fly fishing, but I did a good amount of stream fishing and I have been very pleased with the Patagonia felt studded boots.
I'm going to be in the market for new boots because I want to transition away from felt bottoms. I'm kind of a Patagonia fan boy so I have never really said anything too negative about their products.
I plan of getting these when they come out.
Patagonia's New Aluminum Bar Wading Boots
It is supposed to provide very good traction and has this model has been field tested and perfected over the last year.