You are going to get every possible range of response to a query like this.
I would say that your range options need to be a bit more nuanced, too. Like any product it is *possible* for either a brand name or a no-name to be "much higher quality." I do not know how you would judge this for a case fan other than on the stated specs regarding construction.
Very often, though certainly not always, there is little to no difference between brand name and no name items and there are times they're the same item. Most electronic components are marketed under a number of brand names, and are manufactured to spec by the lowest bidder, and that lowest bidder is seldom forbidden from selling provided they do not reveal the relationship between their wares and those sold by the companies who have had them manufacture for them. Brand names do have reputations to protect and don't tend to wish to have them tarnished by ever marketing substandard materials, but we all know that ever once in a while that does happen (and often not through their fault, but due to fraud by the actual device manufacturer).
There is also the distinct possibility that a no name could be anything from adequate and probably long-lived, though not quite as good as a brand name, all the way down to complete and utter crap.
My approach is generally cost based when it comes to items that provide specs and where replacing them, should it come to that, is relatively easy. A case fan falls into that category. When it comes to anything that requires a lot of effort in order to replace, the equation changes, but only somewhat. I won't risk buying something that I suspect could likely fail under any circumstances. That still doesn't mean I'd go for top of the line, either.
You do your research on what the product purports to be, you pays your money, and you takes your chances! [And that's throughout the cost and name range.]