Its debatable, because I think, there is no organization to do a world wide survey and provide conclusions with statistics of participating peoples. However, I can pitch in with my own opinions : As far as I think, Internet was the first biggest invention, and then the next big was the touch technology ( used in smart phones, laptops or tabs). Probably blockchain is going to be the next biggest one alive, yet to be adopted in main streams. And I have heard Quantum computing is going to be next big thing, to be invented.
So if I choose one of these, then I would go for Internet still, because that's the one which has reached to maximum people.