However I found this:
Best Answer - Chosen By Voters
The pylon mounted engine is much better. Remember also the 727's MD-80's etc. don't use hi-bypass turbofans.
With wing-mounted:
*Weight balance works out better with the engine weight near CG
*Catastrophic engine failure is much easier to manage (although never a pretty thing) because of "Fuse pins" that allow a violent engine to simply depart the plane versus what happened to United 232 in Sioux city.
*Easier maintenance access
*Asymmetrical thrust can be used which is more efficient than the rudder
*Fuel is closer to the engines (less plumbing)