I've tried E-Z Up, Quick Shade and Caravan. I'm happiest with the 10x10 heavy duty Caravans. They are the same units Costco was selling in a bag for $199 and I got them from Caravan refurbed no bag for $99 + frt. You have to call to see availability.
I hate to say it... I really really really hate to say it.
Wal-Mart. I have a First-Up I got from wal-mart, it's a 10x10 and it's top is actually very well designed with a ventilation flap that allowed it to withstand the heavy winds last year at Spokane, while the EZ-UP tent next to it (without the ventilation flap) folded under the pressure.
I also have a 10x15 by Swiss Gear and it is fantastic as well, (I believe it's at WM as well)