All speaker cable is bad.
There, I said it.
OK then: all speaker cable is bad, compared to the theoretical (but impossible in practical terms) ideal of having the speakers directly connected to the output stages of the amp.
So really the 'best' cable is actually the least bad speaker cable - ie the one that messes up the signal coming from the output devices as little as possible.
It's for that reason some enthusiasts subscribe to the US audiophile preference for long interconnect runs between the preamp and the power amps, those power amps being as close as physically possible to the speakers, and connected to those speakers with short 'tails' of speaker cable.
But unless such a configuration is done properly - balanced connections can help in this respect, being less prone to interference - the 'long interconnects, short speaker wires' approach can bring as many problems as it solves.