While I can't come up with a definitive single "absolute favorite cover ever", for this week I'll go with the cover of the comic book that really got me into this mess and started my fascination with heroes from the Golden Age: Justice League of America #101.
As a side note, I don't even own this issue myself.
That summer, my oldest sister was away working at a Girl Scout camp, and she had asked my Mom to pick up the comic books she normally bought herself when my Mom went to the store and was buying her own regular magazines. (This was back before local comic book shops were much of a thing.) While I was away for a week on vacation with my parents in Kennebunkport, Maine, I was helping my Mom find comic books for my sister on the spinner rack at the Rexall drug store in that town, and this issue was one of those we bought for my sister.