It all depends on what the specs turn out to be as well as what you want to get out of having this mac.
If you want to game, probably a 15 or 17 inch if they have dedicated graphics. If you want to do everything else (including photo, music, video editing) go with the basic unless the upgraded 13 comes with a SSD/higher res screen.
Most of the REAL work that I need this Mac to do for me is Photoshop and web development with little to no gaming.
I just want to be sure that this refresh isn't a step backwards from the current 15" models.