Going for silver, which is scientifically proven to never look bad. (Also, it'll match my aluminum "cheese grater" 2009 Mac Pro, which is still going strong.)
From where I sit, this looks like an almost perfect aluminum case. The thick bezel and wedge-shaped solid base should make it highly rigid. Yet, it doesn't have the ridiculous "weight" piece that I've seen in others lately, that only serves to run up costs and compromise the structure.