PC manufacturers?

I prefer to buy my power cables used. I look for cables that are in good condition, well reviewed and fair priced. As I look at my collection, I have a mix of manufacturers and I wonder if that's a good approach...My question, should I find a brand I like and stick with it throughout my system or is reasonable to mix quality cables?
I'd say it is personal preference.   Take a generic 16g cable, swap it, and determine if that particular cable upgrade makes a suitable sound improvement.  If not, sell it, and use the 16g cable until you find something that does work to your preference.  I don't believe the brand of cable makes much of a difference as the construction and noise abatement engineering designed in the cable.
The brand of cable makes a tremendous difference, for the simple reason that all high end cables are designed and manufactured on a very personal level. The designer starts off with a sound he is going after. Then as he builds more cables, if successful the brand acquires a following. At this point it becomes very difficult to make much of a change. Think of a band like The Rolling Stones, imagine they came out with an album of African or South American rhythms like Paul Simon or Neil Diamond. Or in audio, Krell somehow apparently has managed to transform from impossible to endure to warm and pleasing. If only Mark Levinson would. I know. Dream on.

So you find wire you like, doesn't mean there's not others out there even better. So what? We only have so much time here on this Earth. We can spend it chasing endlessly, or we can go with what we know works and chase improvement elsewhere. This more than anything else is why I have used Synergistic Research so much over the years. Thirty years ago I tried enough different stuff to be certain there was nothing better, anywhere. This may no longer be the case. But the only way to know for sure is to compare a whole lot of wire. Which I am not about to do. For sure I would find something better. Equally for sure I could buy something like my Tekton Moabs and have something better too, and with a whole lot less running around shipping receiving shipping trying flipping. Maybe you like that. Not for me.

The trick or key step is notice in the beginning I tried a whole slew of different stuff. But I was hooked in with a dealer who made that easy. Nowadays I glean the same info from reviews. Either way, however you do it, once you find something that really works for you remember:

If it ain't broke, don't fix it.
One brand approach is usually easier, though you match power cord and particular component, so it might not be the best approach. However, mixing and matching different brands can be a nightmare. I would try to avoid it if I could.
I agree with the comment that it's a personal preference. Many look at various power cords as tunning devices to achieve the sound that the listener is looking for, it's not necessary to stay with the same manufacturer however there is nothing wrong with that. The major goal is to achieve the sound you want.
Easier to go one manufacturer, more difficult and continuous search with mixed brands. In the end though both can work.