Assuming you want a sound decoder (Otherwise why ask about Gold?) then go for the Gold. It's cheaper (in most cases). Example: HOGtrainz Atlas RS-3 Gold - $172, Silver $97 - Difference 75$ The cheapest you will find an ESU Nano to plug into the Silver is around $98 (Example
https://sbs4dcc.com/products/esu-58925-loksound-5-nano-nmra-dcc-sound-decoder-esu-e24-integral-connector.html) so buying separately costs you an extra $23,
If you don't want ESU sound, Digitrax does make an e24 socket sound decoder for around $55 street price. But I have no experience with it.
Also, if you're getting the latest release, then the DCC installs for the Atlas RS-3 that have been posted previously won't be very accurate. As shown in this thread:
The New Atlas RS-3s Decoder Installation and Shell Swapping Atlas has modified the RS-3 mechanism quite a bit.
One other thing to consider is that Atlas apparently hasn't released the RS-3 Gold model yet. I looked around and the Silver ones are available but nobody had the Gold in stock. I think a situation similar to the GP-20 where Atlas had to fix something with the Gold versions before shipping them out to distributors.
The point of that being, if you're in a hurry and want it now then getting a Silver and adding your own ESU decoder is currently the only way to go, albeit slightly more expensive. If you're willing to wait for Atlas to release the Gold version, then that's the cheaper way.