1/0 gauge wires, what's the best?

I have used these cheap cables.  There is def less copper in them.  I wouldn't put them in my car, but I do regularly install them.   Its not what I would sell the customer, but its what they buy.  Swap-o-rama special.  The package says it'll handle a thousand watts, must be good right? 

Wouldn't use it?  Don't really have that option.  I need all the install dollars I can get. If a customer brings me a crappy amp kit, I'll tell them the difference, and usually show them the difference.  But if they don't wanna pay for the difference, we use what they give us. 

Some of the main one's that are def sub par:  DP Audio, Phoenix Gold, Diesel Audio, AudioPipe, etc. 

Some good ones: Kicker, Streetwires, Monster, and most of the AMP stuff. 

I wasn't meaning to put you on the defensive either.  Just stating that there is a lot of stuff out there that is sub par.  I work on cars every day.  I've seen a lot of the good and a lot of the bad.  Some people say wire is wire, I kinda disagree.  Some stuff is def sub par, some 4ga is not 4ga, some is so fraile you can barely use it, and some is closer to the size of 8ga.

While I do agree that a true 4ga from a welding shop is just as good as the 4ga from your major car audio brands (minus the flexiblility), some brands are putting out sub par wiring.  You should be carefull what you buy.  Just because is says 4ga and 1000 watts doesn't mean it is.  It might be sufficient to run those particular brands 1000 watt amp, but that is simply because the ratings on their amps are inflated too.  Their 1000 watt amp puts out 150watts, so their 1000 watt 4ga (8ga) amp kit will work great.

Welding cable sucks to run trough a car, period. If thats what you can afford so be it.  We run stinger and memphis car audio wiring and thats all we run. as far lower end wire being just as conductive as higher end wire I think that is a matter of opinion. Memphis released some testing data on this and it clearly shows that output of an amplifier is decreased by using sub-par power cable.  Doing this on daily basis has brought me to the conclusion the better wire is worth it. I do agree some companines use some pretty drastic advertising practices to promote their products and do tend to mis-lead the customers. I also find it funny and sad at the same time how some will run out and spend 400+ dollars on an amplifier and want to install it with half assed cheap install kits then bitch when the product doesn't perform well or they have headlight dimming.