Imo it is difficult to say the "best". On one hand our ancestors finally taking a stick on their hand and using it to more efficiently beat another humanoid monkey was the first step of what we have accomplished now, so that is fundamental for everything that come later, the first step of the power of the brain on the other the best is for sure the most advanced piece of technology we have now. Maybe it is computers and everything derived from it, they are at this point in every aspect of the society: smartphones, regulation of traffic, nuclear power plants, medicine and also it is so advanced it can evolve on its own at this point. Almost all jobs can be replaced by the most advanced machines now. Even if you take nuclear weapons/energy that for sure is a field I would discard compared to PCs and all that is related (a world without nuclear weapons or even nuclear plants that can become another Chernobyl or Fukushima doesn't seem so bad).