While I am extremely fond of silver there is nothing like a nice gold coin when the sunlight hits it just right. Remember the suitcase from Pulp Fiction? The golden glow that emanates whenever it was opened? GOLD.
Really surprised not to see a copper option. I voted silver. It's accessible to many, pretty in pure white and tones up nicely.
Gold is the best for me as it is not only connected with wealth, power and money but as far as gold coins go it's hard to find anything that compares!! Silver is nice but if you can be bold, then go for the gold!!
I really like palladium and am glad it was included as an option, I work with it as well as gold and silver to make mokume gane rings. It is a great contrast to the silver, and the colored golds except white. My wedding band is 14k red palladium and silver. Having said that my dream ring is one of palladium and electrum(50% gold and 50% silver) when I get some extra capitol in( if I don't spend it all on coins).