We consider this 841 the best on the market due to 99% reliability, 2 year limited warranty (this is big for many people), lower DB rating, and actual performance being well above what is advertised. I think many people would be suprised if they actually threw a meter on one of the other brands miners what they are actually pulling with minimal TH increase.
I can only accept that argument if the price is right. If I can buy 3 S9s at the same price than 2 841s I can even throw away the S9s that fail and still make more money.