Not holy-grailing Mintcell bro... but IMHO they are the best quality on the market. I've used some other brands but got 2 fried like hot potatoes.
I've used multiple unknown chinese brand bought on aliexpress and have had NO problems at all. I am running all sorts of GPUs on these risers. 1050tis, 1060s, 1070s, 1080ti, rx470s, 480s, 570s, 580s, and even Vega56s.
There is no need to buy branded PCIE risers, these are pretty straightforward hardware and there isn't really much difference (except with the USB cables) among existing brands.