Ok so I was thinking about mining for hobby, cause I have a steady job. I can invest some $$$ no problem. Still I have to find a moderatly cheap setup to mine and to play with the rig 
Still best option would be Gpus you can buy AMD Rx480 for a small start or Nvidia 1080TI for a better start they would save you some good money. If you have a steady job then my advice will be to invest in mining once and increase your rigs monthly for example you decide to spend $100 per month on your mining hardware. make a small rig of 2 Rx480 that board you select should be expendable for upto 6 cards check the specifications of motherboard on how many PCI slots in total it has. Then next month add 2 cards to this rig. Next month add 2 more cards to it. After 3 months buy a new board and start your second rig. But do not touch your earnings in cryptos. By this time next year tell me how much you earned you will have a very good success story of yourself.