Hash rate - How many hashes per second can the Bitcoin miner make? More hashes cost more, so efficiency is crucial. If you have more questions about the Antminer you can always ask other Bitcoiners for help in the official Bitcointalk thread. The Antminer S9 seems to be the only Bitcoin miner that is still able to create a somewhat positive ROI in the current environment. This is a wider range than the AntMiner S19 series, and the lower temperatures at which it can operate means it may see slightly improved efficiency.
The WhatsMiner M30S consumes slightly more power than the AntMiner S19 series, and is slightly less efficient at converting electricity into Bitcoins. The WhatsMiner M30S and M30S are Shenzhen-based MicroBT's answer to the Bitmain AntMiner S19 and S19 Pro. And AntMiners are incredibly sought after by the world's biggest miners, so it's hard to get your hands on one. Plus, there is always the question of increasing difficulty and how long it will be before the Antminer s9 becomes obsolete (usually this happens in 8-12 months).
Hashage, a local Chinese mining company, has been posting ads on WeChat looking for facilities with 20 megawatts of capacity to house their Antminer S9.If you're interested in getting into Bitcoin mining, the Antminer s9 is probably the only logical solution. Since most people will probably rush to buy the new Antminer s9, you may want to consider getting the older model (Antminer s at a discounted price due to lower demand. Unlike the Antminer S9, S7 or Antminer S5, with the Antminer R4, Bitmain is targeting the home Bitcoin mining market. And these devices don't last forever either, companies like AntMiner are always improving and releasing new versions of their ASICs.
Overall, the WhatsMiner M30S series is a phenomenal Bitcoin miner, with hashing power that rivals the AntMiner. However, if you go down this route it is important to recalculate the cost-effectiveness as the Antminer s7 is less energy efficient than the s9.