which is better speaker cable

Which do you like better? That's the only thing that matters.

If you're open to other cabling, I would like to suggest finding a pair of Audio Tekne speaker cables. Stock, the thin and extremely flexible Tekne ics and scs are the smoothest, most detailed, and musical I've yet heard. Then I had them double-cryo-treated for about $60 for which I realized about a 50% improvement.

Contrary to the high price tags on the Audio Tekne amps and preamps, their cables are extremely reasonable at about $700 for a 1m pair of ics and $1200 for a 2m pair of scs.

-IMO

Considering your amp and speakers I think I would prefer the Nordost as the Cardas has always seemed a bit too laid back for my tastes.

WOW! Talk about polar opposite's, you don't get much more different than Cardas vs. Nordost.

The Cardas will give you a richer, fuller sound, the Nordost a faster, more transparent sound. The downside is the Cardas can sound slow, while the Nordost can sound lean. Not knowing your musical preferences, I would have a hard time recommending one over the other. It's just unusual to see someone considering two such different cables.

Neither is better, just different. You will prefer one over the other, but that doesn't mean it's better, just better in your system, to your ears. That's all that really counts.

For speakers like that, you really should move up the cable food chain, as othwerwise you are doing them a disservice. Try PAD Venustas, which I use and enjoy and used are not crazy expensive, or Nordost Valkyrje, which you can pick up at a good price used. There are others at this level of performance.

Neal