I don't think it really matters. None of our appliances match (brand wise). We just purchased what we liked in our price range. We have s/s fridge, s/s & black range and black dishwasher (the dishwasher came with the house).
When buying all I would care about is that the colours match if we liked them, but if the appliances were old it wouldn't matter b/c we would most likely replace them anyway.