I haven't done any experimentation myself, but, I know people, including small manufacturers of ultra high quality components, who say there is no such thing as a best or top resistor, capacitor, or any such component. I asked one why he worried about a certain "cheap" resistor becoming unavailable, and he said that he had tried many others, such as Vishay 102Cs, and for his circuit, in his opinion, they sounded dry and analytical. I heard the same from another small manufacturer.
It would be much easier if there were such a thing as a clear upgrade path, but, that is not the case. I heard an "upgraded" version of an amp I am familiar with that sounded shockingly bad compared to the original. It turned out that the upgrade consisted of just parts substitutions of Black Gate caps for the cheaper caps the manufacturer used. In this particular application, the Black Gates were NOT appropriate.
It would be much easier if there were such a thing as a clear upgrade path, but, that is not the case. I heard an "upgraded" version of an amp I am familiar with that sounded shockingly bad compared to the original. It turned out that the upgrade consisted of just parts substitutions of Black Gate caps for the cheaper caps the manufacturer used. In this particular application, the Black Gates were NOT appropriate.