StorJ if you have fast internet.
Then mine BURST in background, on free space from StorJ.

how many coins do you get for hard drive mining?
I am not 100% sure if it was SIA coin or if it was from burst. But I did see that a forum member did post that he was making around $18 per month by just renting out their 8tb hard drive.
But from the comments above I want to see if I can stack it like they said where you run storj and burst at the same time.