Diversity vs Uniformity.
For your collection, I pick availability.
When collecting a back run of a player, you obviously are dealing with diversity. When your focus is on a subset of backs, you obviously are dealing with Uniformity.
In your case your focus is on the front, so I would be focusing on what you feel is the best front. A WaJo portrait is a fave amongst collectors. Get the nicest one you can and don't worry about the back.
Good luck on the hunt!