They both have there place. Depends on what you want to spend, what you consider to be accurate (good enough), you and your smiths ability to build and shoot consistently.
Do prefit barrels/ guns shoot absolutely. Not all but most. Same goes for gunsmiths. If you have a very knowledgeable and meticulous smith, a prefit will never be as consistent as a well built rifle from a gunsmith. The tolerance levels cutting threads, truing actions, chambering, fit and finish, ext. These are all things that make a true smith irreplaceable. They do not cut threads, do not time actions, do not chamber each and every rifle the same. There all different just like women (some are easier, some are not). CNC technology is very accurate, but in my opinion it is only as good as the person that designed the program, and only as good as the quality control, and tooling.
A smith that is worth their weight will outperform any CNC machine in timing, chambering, truing, and fit and finish. In the end will produce a product that is more accurate, more consistent, more reliable, than torquing a barrel on with a go no, go gauge.
As stated above a prefit is a viable option and cost point is always something to consider. I have a couple myself, do they shoot yes, but not as good as the ones my smith has made!