HOW TO CHOOSE A SPEAKER CABLE?

Do your homework and narrow the choices down to a couple of manufacturers. Hopefully, this will include a local resource. Then get some samples from each manufacturer at a couple price levels you’re comfortable with to try at home. If available, you might consider borrowing a set of cables a level above where your "comfort level" is. This will let you know what you are missing at the lower price points and set the standard for a future upgrade. You just might decide that taking the leap is worth it.  Or, the more expensive cable could make you feel even more confident with your price/performance/value decision.

Yes, all things being equal, the more metal the better. And, yes, high quality cables can get expensive in a hurry when you "beef" them up.

Good luck.

@akg_ca  "the fatter the diameter of the metal core the better because the electrical resistance between amp and speaker will be lower."

Yes, the outside diameter, where the signal travels, is the important factor of resistance. The core itself can be air, as are some wires. 

Unless you are married to a specific brand, get the purest conductors with the least impactful (on the sound) dielectric, and have at it. For me that is Wireworld Equinox 8. It is composed of PC-OCC copper with Composilex 3 dielectric. I got two 8 foot pairs (for bi-wiring) for $1400 new. Done. 

Worth a look