Hi sepandee,
You're talking speaker cables, right? I don't know what country you're in (posted before your previous post), but here in the US, I get Carol brand "flexible" 12 gauge cable. It's plenty large enough and very functional. It's about $0.50/ foot, so that's about $1.50/meter. I find 12 gauge to be an excellent wire size, and you will not need to question if a larger diameter wire would improve things. If you have exceptionally large runs (greater than, say, 10 or 20 meters), we might want to discuss further. But for anything under that, 12 gauge will suffice.
Big-name brands like Monster don't offer anything above and beyond other "cheaper" cables, like the ones I'm using; you're paying more for the branding that Monster and friends are doing. Other people will disagree, and believe that different cables make a difference in a system. If you can, ask your dealer if you might be able to borrow both and see which ones you think sound better. A good dealer should be able to set you up with something (especially if you pay a deposit that will be refunded when you return one or the other). I think you'd end up with the less expensive models.
Good luck!