Bitmain.  They are the only ones that have consistently met their deadlines and specs and in the one case where they had a small miss on specs they compensated customers proportionately.  Spondoolies is the only other manufacture even close.  It's notable that both of these companies appear to have had their R&D funded by private investment.

All the other manufactures in hindsight appear to be thinly veiled schemes to use customer money to finance R&D which they then use to build private mines once all the risk has been eliminated with other people's money.

Hashfast lead everyone to believe that their R&D had been privately funded but we now know that was false and they were using customer money to fund and operate the company.  Money which was not rightfully theirs since they hadn't yet shipped any products.

http://en.wikipedia.org/wiki/Revenue_recognition