I find the mother turns everything black tho and I'm not really a fan of that.
The black is the brass particles that are polished off. The Mother's probably has more polish in it; i.e. you're using too much of it.
If you add enough polish to your tumbler, and you leave it on long enough, it'll turn black. Even if you load it with brand new cases.
Nu finish has a lot of polish in it. Put some on a cloth and spin a case in it. Compared to most liquid car waxes, it'll polish a lot faster. And turn the cloth black, faster. That's to be expected, since Nu Finish is car polish. Car wax is expected to have less polishing compound than car polish, and some few car waxes even have no polish. Most car waxes have some polish, because it's almost impossible to apply car wax to a clean, unoxidized surface unless you polish it at least a little while you apply the wax. If you polished it first, then waxed it after, the freshly polished surface would have already tarnished a little. To get the most bling, you need to seal the surface as you polish it. Pure car waxes are meant to be "maintenance" waxes to restore the protective wax finish before it is gone. It's for those guys that wax their car every month.
turtle wax finish restorer
"Finish restorer" implies it has more polish than their car waxes. It might be on par with Nu Finish.
I have found that any liquid car wax works ok
One of the big reasons NF is so popular is because of the polymer coating. It doesn't leave the cases near as slippery as when I used Turtle wax. Nu Finish is largely undetectable on the cases. You can also use more of it before gumming up the media to where it leaves blobs of black residue on cases. YMMV.