I do not think that a "Greatest Films" list should be drawn according to subjective taste. That should be the basis for a "Favorite Films" list. A successful artist, in any field, needs an audience or else he is whistling in the closet. The best films are those that reach to their audeince to such an extent that they leave a lifelong impression. "The Wizard of Oz" comes to mind. I am a folksinger and I can assure you that the one song that every audience will sing is "Over the Rainbow". I don't know anyone who hasn't seen the movie again and again. "Citizen Kane" may have been a terrific movie (I thought it was slow moving and self-conciously theatrical) but they ain't showing it in TV every holiday.
Of course, this means that "Gone With the Wind" is up there, too, even though I couldn't stay awake through it. It was like the eternal flame. But, an awful lot of people (mostly women) rewatch it often and get the same, old charge.
This is how all great art should be ranked. Not by personal taste but by universality and message.