Canaan's Avalon 841's. Built like a tank and near indestructible, very easy to tweak the settings for everything covered by the cgminer API (that Kano wrote btw). I still have 10 of them. Most are long retired but I still run 2 as very quiet wintertime space heaters pulling 750-800w yet still delivering ~9TH each.
I was pretty much unlucky with the Avalon 841's, I never liked them, they were never stable and kept failing all the time, but to be fair, I have to make clear that I bought those gears used, so it's very likely the previous owner/s have abused them pretty much, however, I bought hundreds of Antminer S9s which were also used (probably for the same duration) and they performed better.
