Is a High bypass turbofan better than a low bypas turbofan? What is the advantage of one over the other? The JT8D is a low bypass engine and is one of the most used in the world, but pretty much all large jets and 737's use high bypass engines, whats the advantage?

Yes. The ones with high bypass ratios are more fuel efficent. And pound for pound they develop more thrust because the fans act as propellers. (Not joking.)

Ok thanks.