Power Cables - Third Party or OEM

Electricity is indifferent wrt brand names so you don’t need to pay big money, unless you want to, of course.

What makes a good power cable?

• Stranded conductors that are adequately sized for the amperage (14 to 12 awg is typically suitable for front end components, and 12 to 10 awg for amplifiers, stay with the larger size for power conditioners feeding multiple components)
• Twisted pair or cross-connected twisted quad geometry to lower inductance and improve resistance to noise
• Ground wire of the same or larger size as the pos/neg conductors and connected at both ends (counter-spiraled outside of the conductors, and outside of the shielding)
• Shielding - either copper braid, or braid and foil connected at source end (see shielding links below)
• Connectors with solid grip and a high percent copper metallurgy (gold or rhodium plating for corrosion resistance if preferred, but not necessary)

If you don’t want to DIY from raw materials, several well-respected cable manufacturers sell bulk power cord cable that has most or all of the attributes listed above and that can function and sound excellent when constructed with good quality connectors (i.e., Furutech and others).

Links about shielding can be found here, here, and here.

It's not an engineering discussion, it's a marketing discussion. Of course an OEM will recommend their power cords and not the competition's. The oldest marketing pull is trying to convince consumers that using one brand's product (whether it's recipe ingredients or auto parts) is superior to mixing and matching. It works.

I believe the actual equipment you are powering has a good deal to do with which power cable you choose and maybe more. Not just the conditioner, etc.  In powering my Schiit Yggy LIM DAC I tried WyWires, Kimber, heavy gauge basic AC cable, Tara Labs, Audioquest and a couple others.  The older (maybe 10-15 years) Audioquest (long grain copper, (forgot the model but was about $80) made the Yggy sound fantastic.  Almost every cable slightly changed the sound quality (some were bright, overemphasized  highs, etc) and the only seeable difference in the Audioquest is that it had a ferrite core around the cable.  None of the others had one so it’s possible the DAC just needed that filtering.  I do believe that the longer grain copper is also great but the Furutech had PCOCC so that’s not the only valuable area. 
On other equipment I found some equipment was suited best with one cable but that cable didn’t sound good on another piece of equipment.  My take away has been to try various cables and trust your ears to hear what sounds best in your system and suits your musical taste.  
I don’t believe you need to spend $1000’s on a single cable to get great sound.  After working in the high-end audio manufacturing field several times over my working career and seeing how things work, I believe the only reason for excessively priced cables is that the company needs to charge a high price to stay in business!  This is not to say that cables going $1000’s don’t have the materials and quality to actually go for a few hundred dollars.  Just not what they are charging. 
I remember years ago talking to our marketing manager about pricing a product.  It’s was a new item that actually cost less to produce and sounded better than the previous product.  We said if we lower the price we’ll sell a ton of them!  He said “but customers relate the value of the item to the price they pay. The item would cost less then our competitors and the public would think ours isn’t as good because it’s cheaper”.  He continued “So even though it’s less expensive to make we have to price it so people see value!”.   I’m still blown away by the statement and have seen it in practice in most audio companies I’ve worked in.  The one company I see trying to provide good product to the mass market is Schiit Audio.  I’m sure they’re a few others but they’re few and far between!  No I don’t work there.  In fact I’m retired so I’m always trying to stretch a buck!!!

as long as you're not using crappy OFC wire which some of the most expensive wire companies use that's junk use OCC single crystal round wire or OCC single crystal rectangular wire which is even better than the round either silver or copper will be very good much better than the OFC stuff at any price they charge.

When I had a BPT conditioner, it sounded best with their top of the line power cord...though in general I find power cords somewhat less predictable than other cords/cables...