I'd say it depends on your most common use case.

If you generally game in a dim or dark room, go with QD-OLED. It has better HDR color saturation, and the panel uniformity is more consistent (ie: doesn't generally have banding problems). The latest 5th gen panels have also greatly reduced the purple color from ambient light and is more a dim grey, as well as using a true RGB stripe meaning better desktop text rendering and reduced color fringing on high contrast edges. The main issue with QD-OLED apart from the ambient light handling is it still isn't bright enough to avoid ABL (Automatic Brightness Limiter) on the desktop with SDR content, meaning the screen will noticeably change in brightness depending on if you have a full screen white background like many websites or text documents might have vs anything with a darker background unless you significantly reduce the default brightness for SDR. Again, not a huge issue if you mainly plan to use the monitor in a dim room, but potentially an issue in a well lit room.

If you generally game in a well lit room, especially one that gets a lot of sunlight, go with the Tandem RGB WOLED. These get noticeably brighter than the latest QD-OLED panels, and the panel uniformity issues aren't really apparent outside of a very narrow range of dark grey colors when in a darker room. They also get bright enough that the screen doesn't change in brightness regardless of the content displayed when viewing SDR content. It also gets a lot brighter in HDR especially in real content. The 5th QD-OLED panels do reasonably well against Tandem RGB WOLED in test patterns, but in real content they are noticeably dimmer. But, while WOLED is brighter, it's also less saturated, since most of its brightness comes from the white subpixel it has. Newer WOLED panels like the Tandem RGB and previous gen use an RGWB stripe subpixel layout which is far better than the RWBG subpixel layout of the first few generations of WOLED, and arguably better than the triangular subpixel layouts of pre-5th gen QD-OLED panels, it still shows a bit of weirdness with text rendering compared to a true RGB stripe subpixel.

So, which is better? A lot of reviewers say the Tandem RGB WOLED panels are superior. But I'd say it really just comes down to how you plan to use it, or if you prefer higher saturation vs higher brightness and how much ABL bothers you with SDR desktop content. Really, they're both excellent options, and even the older panels are still great. When it comes to response times and motion clarity they're stunning.

That said, some people who really like very bright HDR won't find any OLED to be particularly impressive. High zone count mini-LED backlit LCDs, be they IPS or VA, are still much, much brighter overall, often capable of hitting their max brightness on full screen white where as OLED can generally only do their max brightness in a very small window or on something like a starfield with lots of single points of high brightness. The starfield example being something mini-LED screens fail spectacularly at. If you want HDR that can literally flash bang you, you have to go mini-led. If you want HDR that can do high contrast, get OLED.