I was wondering which brand of miner is the best one to buy to start to mine bitcoin currently? Need experts' advice and suggestions.
It depends.
If you want the highest performance and efficiency, the Bitmain Antminer S9 models - but they are widely known to have reliability issues.
If you are more worried about reliability, the Caanan Avalon 741 has a very good track record, at the price of a little lower efficiency and lower performance than the S9.
EBang BW.Com and Hotmine don't have as many units in the field in the hands of non-large-mines so their track record is a lot more "unknown" except for the large farms that have lots of their units.
Innosilicon dropped out of making SHA256 miners entirely, but the ones they DID make were rock-solid reliable - it's a major bummer that they didn't move into the 14/16nm generation.