Bitmain is the only choice for Bitcoin Mining
Why do I say this?
I have purchased 267 Antminer S1's. Out of 267 S1's I have had 1 problem unit. One unit with a dead ASIC blade. That's it, 99.8% success rate. That's unbelievable. They just keep running, and running smoothly.
I have purchased 27 Antminer S2's . Out of those 27 S2's I have 1 blade that only half worked (From batch 1. The heatsink had a burr on it that cut into the board and shorted out half the blade). I also had 1 power supply that melted as the cables weren't connected tight at factory. While batch 1 had a good amount of extremely irritating issues, batch 2 was much better and batch 3 was nearly flawless (A few loose internal cables). I have been in contact with Bitmain concerning all the issues and they are indeed working to correct where they have come up short.
I have no doubt the S2 will soon be just as rock solid as the S1, and as you can see form above, the S1 is gold standard in ASIC hardware.