Tellurium copper (or even berylium copper) would be superior to brass or bronze, yet strong enough and elastic. Brass is a legacy, historic material but also obviously cheaper to make connectors from. While it is great for general use it's not the best available yet affordable option for hifi.
However makers of connector still mostly refuse to accept that minimum metal mass is a way to go for hi-fi instead of massive, heavy connectors which have to fight Eddy currents. Also, heavy nickel plating under gold or silver finish plating is still preferred over direct gold/silver plating just because it gives that nicem looking eye-candy effect gloss. Seems many manufacturers prefer eye candy gloss or massive approach before what's best for the sound. However wise ones will choose otherwise if they have an option...
However makers of connector still mostly refuse to accept that minimum metal mass is a way to go for hi-fi instead of massive, heavy connectors which have to fight Eddy currents. Also, heavy nickel plating under gold or silver finish plating is still preferred over direct gold/silver plating just because it gives that nicem looking eye-candy effect gloss. Seems many manufacturers prefer eye candy gloss or massive approach before what's best for the sound. However wise ones will choose otherwise if they have an option...