The most widely used spark plug cables are those made from a carbon core. Carbon conductors are used by nearly every automotive manufacturer and found on pretty much every vehicle today. The reason why they are so popular is their ability to suppress EMI. Magnecor wires suppress both EMI and RFI so there is no interference with the engine computers or various sensors.
Magnecor ignition wires are the most efficient at transferring the spark energy to your spark plugs. Unless you are using a very old vehicle or engine, then you need your spark plug wires to have EMI suppression. If not, the engine will run poorly and you will not have a clue as to why.
The other upside to using carbon conductors is how cheap they are to make. Magnecor ignition wires are very affordable for what they provide for both your OEM replacement wire needs and high performance race wire needs. Carbon has a great life as well and do not have any life limitations, although most original equipment manufacturers see them as service parts.
The one thing carbon is not good for is when you have an aftermarket ignition system since they cannot handle the added spark. For this reason, the customer should use Magnecor race wires which use wound wires typically from alloy or stainless steel. This is a more efficient way of handling the spark. Spark current is also reduced when you use Magnecor wires, and the low resistance helps transfer the spark energy better.