I have done a fair amount of comparison on some different RCA panel mount females.
My favorites are (in order of sonics):
WBT NextGen Silver
WBT NextGen Gold Plated Copper
Vampire Gold Plated Copper CM2F/CB
Cardas Rhodium Plated brass
The Cardas wins on value.
The WBTNextGen wins on best sound.
The Vampire is very sturdy, but is rather expensive and is a solid billet of copper.
I do prefer the sound of a connector with a minimum amount of metal.
For RCA cable mount males, The WBT NextGen Silver is on top.
The WBT NextGen Gold Plated copper is just a hair better (IMHO) then the Eichmann Silver Bullet Plug. Next is the Gold Plated Copper Bullet Plug. Then is everyone else

I recently received some WBT NextGen binding posts. I will be trying them out on an amp project soon. I like the sound of the Eichmann Cable pods but there may be some durability issues with them. The Superior Electric Gold Plated Binding Post are very good sounding for not a lot of money.