Here's my unsolicited opinion on some of the items being discussed here...
Defining a "quality" light as one that works perfectly and reliably off the shelf from day one to day one thousand, affordable lights sold direct from China, like those from DX, KD, and yes, even CNqualitygoods are not "quality" lights. (I'm looking at the DRY and frankly, between the battery carrier and the disclaimers, I'm underwhelmed).
However, for a somewhat handy DIYer, affordable (and modest) lights from these and similar sources can be just fine. I mean that not just as a starting point for a custom project where most everything but the host will be replaced, but even with their stock components, just rebuilt. Lights like these often just need proper reassembly which takes time and care that the manufacturers simply can't afford to spend on them and stay within their profit margin.
For the most part, the machine work on the more common pseudo-brands (UltraFire, Romisen, Aurora, MTE, etc.) is acceptable. It's been a long time since I've cross threaded or stripped anything from these sources. Also for the most part, the drivers, despite being generic and unimaginative, are acceptable too.
By my experience, all it takes to turn most cheap lights into lights of a higher quality is a rebuild. That means stripping the light down to its components, cleaning everything, and properly reassembling. That means also desoldering the LED leads from the MCPCB, removing the MCPCB from the pill and removing all the silicone goo they use as thermal adhesive. Reassmble using good thermal paste and perhaps shim the space between the MCPCB and reflector with something non-conductive to ensure pressure is applied to the top of the MCPCB. While you're at it, take the time that they didn't at the factory to perfect the focus of the LED in the reflector. It's time with a soldering iron, a file and some steel wool that you wouldn't have to spend on a quality light, but for some of us, time spent that way accounts for more than half of the hobby.
Having said all that, I have to add my personal opinion of every 3 XML light I've seen in the budget category to date. To me, none appear to be appropriately equipped in terms of heatsinking or battery capacity to run the XMLs at high current. If the intended purpose is only for a lot of soft flood, meant to be achieved by running each XML at a max of ~1.5A, then I think these lights have potential. If the desire/expectation is for a genuine 30W of LED power applied practically, look elsewhere.... custom builds from experienced and capable modders.