All of them have ups and downs, Rawtherapee is fast bug buggy as hell and has no adjustment layers, Capture One is marvellous but has political problems with supporting files from the medium-format Pentax, ON1 Photo RAW is a freshly released piece of software and it managed to crash on my images.
I don't think I can agree that it's a pity. Lightroom is the standard for photographers right now for pretty much everything but fashion photography (Capture One) and perhaps architecture photography (DXO Optics Pro). Everything, including the competitors you mentioned, is compared to Lightroom.
I think these applications (including DarkTable) need to be compared to Lightroom because the point at which they're competitive with Lightroom is the point at which they become seriously viable to many photographers (the kind that don't necessarily hang out on HN).
I use DxO for all of my photography. Because Lightroom slows to a crawl on my imports, I haven't really tried it for RAW development. I guess I should give it a go. However, at this juncture I fully believe that DxO is miracle software. I've gotten far better results with it than I have with anything else. DxO can take a trash shot and make it 80% and it can take a good shot and make it 500%. Far more impressed with it than ufraw and the other RAW development suites I've tinkered with in the past.
The lens/sensor RAW optimizations are fantastic (provided your camera has a bayer type sensor -- sorry, Fuji X users) and it can definitely make your photos punch above their weight. Depending on what you do, it might be worth spending more on the Elite edition -- most people don't need it, IMO. There are paid upgrades yearly, but if you don't need the new features, you can choose to skip a version (or two).
There are a couple of sister products, DxO Viewpoint for perspective fixes and DxO Filmpack (filters). IMO, Filmpack isn't worth paying for, but if you do a lot of architectural/wide angle work, Viewpoint is pretty good.
Also worth looking at is Affinity Photo - it's half the price of DxO. I bought it as a cheap alternative to PS for PSD editing, but it does RAW processing too.
I also find that when I process with Capture One Pro, I nearly always get better results than when I use DXO, RawTherapee or Darktable. Maybe it's just me but it is consistent.
However, IMO DxO's output is leaps and bounds better. I'm sure it's due to the profile of the image, and specifically DxO's PRIME noise filtering since this was a handheld shot at nighttime, meaning high ISO (3200). The noise filtering from DxO is hugely superior to that from Capture One. Without PRIME (i.e., marking "high quality" noise filtration instead of PRIME), the noise filtering is at least in the same ballpark, but DxO maintains a very sizable lead with far less color damage. I did try to set the filtering configuration settings to similar quantities, though the options are a little different in each program.
I may make a blog post with images on this subject soon.
Since getting a full frame camera though, I find noise isn't nearly as much of a problem and Capture One's noise reduction is fine. Certainly not as good as DxO but I don't do much low light shooting.