Photographers are always searching to find why certain photographs are more inviting to the eye then others. I have listed ten qualities in photography, and for that matter of all visual arts that I believe are pleasing to the eye that are typically included in a great photogrraph. Not all be present in each great photograph but many can be seen in most excellent photographs.
Simplicity order and clarity
Contrast strong but not excessive
Detail that is sharply defined
Texture that gives surface life
Form that is simple and bold
Outline that is suggestive and crisp
Pattern rhythm and repetition of related forms
Depth in the form of receding lines or objects
Motion that indicates aliveness or action
Spontaneity animate the subject
Hope this helps you in taking some great photographs!