I think there are so many ways to make connectors and wire, and so many variations of metals based on purity and how it is drawn, annealed, etc, that categorically calling a metal better or worse is often too little of the story to be complete.
After messing around too long with plated wires and never loving them except on occasion, I started cutting out the middle man, and going for more carefully made things that were not so much designed to save money.
Since then I have used soft annealed 999 silver in oversized teflon, UP-OCC silver in oversized teflon, 5N in cotton, UP-OCC in cotton, UPOCC in teflon .... and though all of these were nice, and having good specs and reviews compared to many, the UPOCC were all better in terms of everything.... speed, translucency, complexity, air, smoothness, etc, etc. Oversized teflon with UPOCC is the most natural and complete sounding to me, but more difficult to do and use...I use it most as ground for interior cable geometries. Factory teflon wire I tried has more shimmer. Where cotton tends softer and smoother, equally "good." But for regular use, all-in-all, Neotech UPOCC silver/teflon is my favorite.
Same story with coppers... I have tried similar variants as with silver, and the same results but with that particular copper "sheen" and complexity that quality copper has. That said, though I use it in places, sometimes in combination with good silver, and/or silver/gold.... I like it as a mixer, but not exclusively in general. Even in amps, to me, UPOCC copper has more self-sound than UPOCC silver so I use it mainly when silver is "too much," and needs a little moderation.
As to connectors. I have tried lots.... RCAs, XLRs, and binding posts, IECs.... and as with wires, everything apparently matters... all materials, thicknesses, low mass versus various levels of higher mass.... And to me, with quality materials and designs, no rules seem to hold up about this or that one being better or worse... Though I recognize tendencies for sure and use them in design, which is "better" can often depend on what I am putting these ends on. For RCAs, of all I have tried, I prefer low mass... though one wildcard in this concept, DHLabs component RCAs seem nicely resolving and "out of the way" to me.
For ICs KLE are my overall fav ends considering sound and value. Even if price were no object, I might prefer the plain purity of sound from KLE Absolutes over the more obviously clear and resolving WBT silvers. I stopped using copper ends on ICs years ago, preferring high quality silver. I might feel differently about some really nicely made UPOCC copper ends though. And lower quality "sharper" sounding silvers I can't really get into either. Or some of the pop retro cable ends like switchcraft... can't really use them here... too slow and masked for me.
For power, of all the "copper/gold" cable ends I have (Furutech, Neotech, and a nicely made one from a Chinese maker, all sound different though they share that gold on copper sound.... The Neotechs have UPOCC copper, and the others "pure copper." I think I can hear it too, the Neotechs more fast transparent and neutral, though not necessarily "better." Depends on how a cable needs to be tuned. I also have some pure copper, and some pure copper with very pure silver plate.... Then Rhodium on copper. My favs of these Rhodiums are actually pretty high mass, with carbon covering... looking like Furutech (maybe OEM?), but coming from a Chinese seller at a fraction of the cost... And I get great sound from these in the right cable, and right component.
I have a lot of cables I have made/explored (using ready-made Furutech and Neotech cable) and making my own, and trying different ends. And each raw cable seemed to excel with "the right" end, and that depends on the cable's wires, coatings, gauges, geometry, damping, etc, etc.
Having tested these things over and over, I never pay any attention to the classically quoted conductivity specs simply because what I hear is what I hear, and I am not concerned about specs if it sounds better to me... That said, with some rhodium ends I have used in ICs, the Rhodium can tend to brittle and hard, but in others, those same traits more refined, they sound clear, smooth, dynamic, and solid. And these traits work better with nice UPOCC wires, especially bringing out copper nicely, and the good quality copper, richening and making the Rhodium sound more complex can be a nice blend. So no matter the metals and constructions, to me, if the end is good quality, with good materials, it will sound good in the right setting, but may not be as good in another...
Finally, I have made a lot of cables, ICs, power, and internal hookup, and as far as I can tell, if they are high quality parts, they all have a sound, but there are not a lot of exclusive "right or wrongs" as to the particular metals used... that is if it is done really well.
Also, to me mass is pretty big, often times lower mass seeming more open, faster, complex and complete....and more mass, more full/thick and forceful. That said I do have a few heavy connectors or cable ends I prefer, but overall, many that are lighter I like better for shear reference spaciousness and resolution. Same with cable gauge. Whether power, IC, or internal, I am always finding a delicate gauge balance to be more complete and working across recordings, doing it all better than a little bigger gauge or a little smaller for a given position.
Interestingly, all four heavy connectors I like involve Rhodium... The "Furutech" carbon NCF power cable ends, some "Furutech" NCF balanced ends (same basic design, both Chinese) a "real" Furutech Headphone jack on a UPOCC copper cable, and some Cardas binding posts with silver plate on quality copper with a Rhodium "flash." These are all heavy, and I can't hear a problem. The Cardas copper/silver/rhodium binding posts are in my amp just now, and they were a pretty pronounced upgrade to the Stock Torii IV binding posts... I put them in after a lot of PS bypass exploration, as well as coupling caps, interior wires, resistors, etc... and it was really notable, my wife thinking this may have been the most obvious single upgrade up to that time (now many years ago). They actually felt louder, but it may have been mostly that they were more fast, resolving and spacious sounding. Not sounding "rhodium" to me... they are just a really nice posts.
And let's not neglect geometry and damping, to me two huge players in cable sound when using transparent materials.
BicycleJoe,Thanks for the reminder of the Walker silver coating. I got some years ago, from mapleshade, which memory says was based on Walker's... but then memory!@#$%^&* I liked it back then though. But then I thought it started sounded a little dulling and thickish, though pretty resolving... a weird feel. I had a similar issue with Deoxit Gold until finding it was a little thick and dull sounding unless I quickly wiped it off, leaving a very thin coat. Then it was really pretty good sounding... improving things. Then I tried Cardas, and it worked really well without a lot of rigamarole so used it for some years. But finally, one of the best clarifying contact enhancers I have tried was Graphene oil by Madscientist. I got a little bitty tube sample and it has lasted for a long time... just a very thin coat quickly wiped off on interior ribbon connectors, or cable ends...and it does that good enhancer thing nice and transparently.
Anyway, after all this, it seems that, like cables, wires, and ends, there are a lot of ways to make contact enhancers better or worse, including application. Having a better handle on all this, I have been meaning to retry the Mapleshade... Maybe I was using it too thick...so thanks for the reminder. I will try it once I finish this. Also maybe I will try it thinned down with some Squalane oil and add a touch of graphene powder. Could be good, so thanks for the reminder.