Well, the thing about Silver is it is the most electrically capacitive metal (least resistance?) on the periodic table. Copper is second, gold's not particularly amazing. The best thing that can be said about a gold-coated plug is that it doesn't oxidize (corrode, rust, tarnish) so that the contact is solid, but an all-gold cable wouldn't work very well.
Gold as a raw material may be more valuable, but I don't remember which is rarer. A silver cable with a chrome plug would be fine/happy for me.