There is money in ASIC miners (of which the Antminer S9 is one). The
Profitability calculator at Nicehash is relatively accurate, and says that at a cost of 10 cents/kwh, the S9 will make roughly $23.68/day. Also, it shows that a 1080 would make roughly $100/month before electricity.
The issue with ASIC miners, though is that they are hard to come by. If you order them direct from Bitmain, there is about a 2-3 month wait, in which profitability WILL go down, and you will also not be earning money during that time. If you buy them secondhand or from a reseller, there are huge markups.
Plus, you need to buy the power supply (usually $200-300) and they are LOUD and HOT. More so than a GPU mining rig. From what I am told (I don't have any ASIC miners), you would not want to have one in your apartment, but if you have a house with a basement, you could put it in the mechanical/furnace room in the basement and be okay with the noise.
Finally, if you decide to get out of mining, it's much easier to resell GPUs to gamers than it is to resell an ASIC miner. Even after GPUs are no longer profitable for mining, there is still a market for them for use in a PC, but once an ASIC miner is no longer profitable, there is no resale market for it.
All and all, GPU mining is easier to get into, and less risky. Bottom line: do your research before getting into mining, GPU or ASIC.