About six years ago I had the opportunity to try a small variety of cables made by AudioQuest. At the time I owned one of their least expensive star quad cables, a friend loaned me his which were a couple series higher for one set and much higher (over $600 per cable) for the other, and a audio store loaned me a set costing even more. I spent a couple weeks comparing those against 12 gauge speaker wire and 16 gauge speaker wire. The lengths were all 6-8 feet. I had Martin Logan Vista speakers at the time.
After comparing, I came to the conclusion that the expensive cables resulted in less treble and what I had been using was ok. I then purchased some 4 conductor speaker cable which was 14 gauge and twisted the red and black together, and the green and white together, with each pair effectively equalling 11 gauge. This is what I was happiest with and used until recently. I'm still using the same cable, but I twist all 4 conductors together resulting in an effective 8 gauge with which I am even happier!
Resistance, capacitance, inductance. It becomes overly time consuming to examine how these electrical properties interact with each other. I purchased some test meters to conduct tests to measure the wire I use to help explain why one is different from another. So after having spent a great deal of time leading me to what I currently use, I now simply enjoy the music.
The wire I bought is: Cable Matters 14 AWG CL2 In Wall Rated Oxygen-Free Bare Copper 4 Conductor Speaker Wire
If the wire is 10 gauge or less, I prefer to use bare wire. I forced myself to use banana plugs and soldered the 4 twisted together 14 gauge wires into an appropriately sized banana plug. The banana plugs I bought are a springy type which stays tight and are all metal construction.
A wise man on this forum has said many times, "let your ears decide". Thanks Roberto.
edit: oops, I took too long typing my reply. Roberto beat me to it.