Bitmain is the manufacturer of Bitcoin mining hardware, and makes the most efficient mining hardware available on the open market, the Antminer S9. Bitmain have been making mining hardware for a few years now, and seems to have one of the best reputation in terms of delivering what was promised. Bitmain delivered their first Antminer products around the time Black Arrow was failing to fulfill customer orders. Unlike many mining companies, they have always delivered.
Their first Antminer, the S1 which boasted 180 GH/s:
It is difficult to profit with an S1 now unless your power is free, but they achieved a good ROI for their buyers.
They have made many hardware generations which has a good reliability history, although the current batches of S9 have had a few issues with burned boards. These can be fixed under warranty but result in lost mining time. The latest Antminer S9 units offer 14 TH/s. The antminer S9 below, boasting 14 TH/s (up to):
They also support the home miner with their Antminer R4, which is a miner aimed at home miners; quiet and reliable at 8 TH/s. These are designed with very low noise in mind for the home miner, and use a special fan design and chip placement to achieve this.
They are continually developing new hardware, and they offer a cloud mining service which is probably one of the few legit ones, although it is still hard to profit with any sort of cloud mining. It will be one of the few legit cloud mining sites however.
They will undoubtedly bring out the latest greatest miners other than the S9 at some stage, but for now they offer the best mining hardware in town and the best service of any mining company in this industry, so they are recommended! They also keep the home hobby miner in mind as well, with development of products like the R4. If you wish to order mining hardware for Bitcoin / SHA256, these are the best game in town as of the end of 2016 for this.