I look at a variety of elements:
color
texture or pattern
pattern of the quilt
how the quilt is made: is it well done or just plain sloppy
the backing and label
the quilting
the overall effect
the story of the quilt
It takes it all to make it work for me.
Some quilts I love even though there might not be much contrast. Other quilts have the contrast but the textures are so equal that the overall effect is more than just disappointing.
ali