Perhaps an interesting variation on the question might be "Do glider pilots make better PPL students?"
Having learned to glide first, I would say that flying a glider develops more control co-ordination [lack of engine to pull you around corners, longer wing span requiring rudder assistance etc.] and this is an advantage.
However, glider pilots also bring prior flying hours to their training, so they have:
(a) previous experience in the environment (b) basic airmanship
(c) perception of height, speed and depth, especially in the landing phase
This is likely to give the impression of them being "better pilots" at each stage of the PPL syllabus, simply because they have more "stick time" than newbies to flying.
Their ability to cope with the multi tasking world of flying should be enhanced by their prior experience.
Of course, there is no such thing as the "average" person, som there will be exceptions.