Unplated copper spades/banana

Re: the tarnishing of bare copper, well, if you have a strong preference for how a bare copper connector sounds, you will likely be willing to have to do some periodic maintenance to clean it. Spade = best chance for better sound, Banana = more convenience.

This same question can be applied to power receptacles and power cord plugs and IEC ends. It's not a matter of one being better than the other, they are just different. I comes down to personal preference and what you perceive as a good or poor match up with various combinations of wire and the connectors. Also, a specific combination of wire and cable can be perceived as good on one component and less good on another component. It's variable.