Totally your preference. This only becomes a question if you are planning to sell it. Most would chose the photo cover for resale purposes unless the art was done by someone of comic fame/lore. For example my Ash Gonzales covers are damn near perfect, in my opinion, but he is not a well known artist and thus the value on the open market is questionable. Again, I am not collecting to resale...I chose Ash because he does excellent work, is local, and is not terribly expensive. I have both photo covers and OA in my collection and sometimes both for the same character. Its all what you prefer.