There is no “best”, I have both brands and also all three types of receptacles (all-Cu, all-Cu gold plated, rhodium plated) with no discernible audio differences between them.
The receptacle plug coatings (gold or rhodium) are alternatives to primarily reduce oxidation , and they are not tone controls . I would also not get hung up on the imperceptible lab test published technical variances on transmission /connectivity .
My gold or rhodium plated All-Cu ones are still overly soft and malleable ones that require care and patience in reefing down the screws for attaching the power cable wires . I would avoid them in circumstances requiring repeated detachable power cord plug-in /plug-out circumstances .
Frankly speaking, in my experience, these wall receptacle tweaks were admittedly a very poor value for money IMO and even a questionable upgrade over my other “normal” hospital grade quality build ones. I would not repeat it again.
Intuitively running dedicated power lines and for each of the source and amp was the key audio performance improvement creator - not the wall receptacle.
Let’s also remember that the trunk power lines from the street to your lot line in many established neighbourshoods are frequently aluminum. The link into your house and to the wall are copper . Hospital grade receptacles are all you need as the final piece IMO.
