Im happy with my 1080ti's, since i dont have much place for rigs this is best option, best hashrates in 1rig, lot of algo's to mine (u will need research), longer roi tho... but with 0 power costs i wouldnt give a fk about roi, u will roi anyways
also got some radeons but as a hobby miner i prefer nvidia
about asic's are more plug n play, also since im a fan of gpu mining i dont recommend asic's ;]
I have been thinking about expanding but waiting for new gpu's
After u roi, u will expand, and you will get to the point when your small warehouse wont be enough for more rigs ;p so better buy something small but powerfull