My question is if it's still worth buying Asic's and start mining BTC in 2018.
If not mine BTC what other coin is it worth to mine nowadays?
In addition to bitcoin there are many other currencies worth exploring. Litecoin is a coin worth exploring. Litecoin has a limited number of 84 million units, while the maximum number of Bitcoin is 21 million. In circulation there are about 54 million Litecoin and 16.7 million Bitcoins. Litecoin aims to reduce the time required for new transactions and refine Bitcoin's exploitation methods so that anyone can participate.