conductor versus cross section
Guys,
The obvious difference between plug wires is the thickness of the insulation around the conductor. Usually, the thicker the insulation, the better the performance of the wire against breakdown of the insulation due to heat or mechanical forces. Also, the more resistant to arcing or damage to the core conductor.
Most center conductors are some type of carbon or graphite based material in a flexible media. Too much flexing can cause a high resistance point in the conductor which can cause a point of failure. Many race applications use more converntional conductors like silver plated stranded copper. The problem with that on a street engine is RF noise and magnetics
As stated above, stock wires are probably best for most applications. If you feel it necessary to get other wires, look at the center conductor technology before looking at the thickness. The length of wire on our engines means the wire is less likely to be damaged by heat or mechanical effects.