The shuttle was highly specialised and quite delicate. It could only accelerate at four gravities and in the challenger disaster, fell completely to bits when turned sideways against its direction of travel. An airliner would have at least held together and an apollo command module wouldn't have cared much at all. Apollo could aerobrake at 11 gravities and because of its triangulated structure could actually take a lot more of a beating than its occupants. It could land anywhere on earth, in smaller places than even a helicopter would require. The shuttle was limited to a few very long runways.
Because of its modular architecture, Apollo could have been extended for deep space missions. Attach an extended service module for long duration. Maybe build a skylab type module as a cruise stage habitat.
But my main point is that shuttle was limited to low earth orbit by its poor aerobraking capabilities, while Apollo flew to the moon and would have coped with missions to near earth asteroids. That makes it a better space craft.