antminer? rx 470? rx 480?
Anything else?
I've heard there are sites that way
*Fastest time to break even
ROI is a measure of total (as the name suggests) Return On Investment
Fastest time to break even... maybe something like the Antminer L3+ Batch 1 or 2 but that ship has sailed
Maybe the baikal mining rigs, those are due to break even in about 3 months
Or as others have said the 1080s
Best ROI... really comes down to total monthly yield, minus capital employed, plus scrap value - which is likely to be GPU based hardware since it can be repurposed for gaming and rendering etc after its life as a miner