Sorry to pull a Bill Clinton, but it depends on your definition of value. Some people (me included) value all original, others value a 100 point restoration and others value a "hot rod". And then there all of those inbetween. So as you can imagine, it can be one giant pissing match as to which has more "value".

On a monetary scale though, I would say all original is a better investment because usually over time that monetary value will go up. A restoration can be very pricey and it takes a much longer time to recoup the investment.