As you can see by looking at my system, I have a good amount of experience and have ended up purchasing as much Argento stuff as I can afford. My IC's will switched to Argento as well once the bank account recovers.
I have extensive experience in conducting power cord tests both in my system as well as at several friend's places that I am intimately familiar with.
So just because it is easier to do, here are some top notch competitors that I haven't heard; Isoclean Supreme Focus, JPS Labs Aluminata, Stage 3 Zyklops, Stealth Dream, Jena Labs Model One, Nordist Odin & Valhalla, Elrod Power Systems, Purist's newest with the box in the middle (heard the Anniversary though). So some stuff in there that is probably really good that I just haven't been able to thoroughly listen. Have heard a few but not in systems I knew well. But outisde of those, I have tested via shoot outs and long term sessions close to 40 others.
As for Argento, the only cable in the Argento PC line that isn't incredible is the Level .5, but even that cord is more musical than a Shunyata Anaconda Alpha Helix. But it has some flaws.
An Argento Level 2 Mk 2 betters the Shunyata in all ways, except perhaps soundstaging.
Then the Flow series takes it all up another level, with the Flow Master Reference being the equivalent to a major component upgrade on my system as well as a friends. It is a ridicoulously expensive cord, although in line with many of the other big name cords listed above, but well, everyone should just have to hear it. That FMR brings a smile to my face every time I think about what it did for my system.
I also have the entry level Serenity speaker cables, which aren't entry level by any standard other than their own product line up. I have owned Tara Labs, Tg Audio, Ensemble, Analysis Plus, Audience speaker cables in the past. They are a big improvement over any of those, but none of those are super high dollar. The Ensemble set at about $3200 new being the priciest. Ensemble would rank third behind the Serenity then TG audio. I love these cables, but they are staying only for length of time it takes me to afford the Flow speaker cable.
The new Flow series just takes everything up a notch, and by all reports betters everyhting in the Serenity line, yet costs a bit less.
I also have a little experience in a friend's system with him deciding on a balanced IC between his CD palyer and preamp. We compared an Audioquest Sky, Purist Venustas, and Serenity SE. The Serenity was the cheapest of the three at the time, but it was easily the most musical, and just no big flaws. He bought the Argento.
If you want more info on Argento cables and experiences of guys who have compared them against just about everything, no matter the cost, go to Audioexotics.hk
Hope that helps.
But yeah, I really like Argento.