Other than length of pull how many variations of fit are allowed by makers of synthetic stocks? Can you specify cast (either on or off) toe in or toe out, cant, specific grip arc radius, diameter of grip, forend taper or profile or a number of other dimensions which may be accomodated in a true custom wood stock. Granted you can add a bit of dimension with body filler but modification of a synthetic stock is largely limited by its' outer skin. Which isn't to say a good glass man couldn't do these things only that it would be very time consuming and I haven't seen any sign of true custom fitting with this type of stock yet.
As has been previously stated custom is in the eye of the beholder but a fine walnut (e.g.) stock that is properly made to fit only you is a work of art. It also costs a heck of a lot more and may not be necessary to your needs. I like good wood but may make up a synthetic for my own use one day. I'll carry it in the canoe where it can serve a dual purpose.
