RawTherapee has:
darktable has:
It’d help if you described your workflow, what other tools you use, and what features you’re looking for. You can’t go wrong with either one, but it is just down to personal preference.
ditto.
I assumed that wasn’t meant to be taken seriously. After all, who owns a garret these days?
Shameless rant:
dt’s exposure Mode=automatic, which is ported from Magic Lantern’s deflick.mo is somewhat powerful, or we are talking about different things when talking about “auto exposure”.
Equalizer.
Plus, nowadays we have local laplacians, e.g. look at exposure fusion in basecurve, and local laplacian filter in local contrast module.
On the other hand, highlight reconstruction is better in rawtherapee, because there is no highlight inpainting in darktable. I keep meaning to write it, but…
darktable’s exposure module is nowhere close to RawTherapee’s. If all I do is open an image and set the exposure module to ‘auto’ in both programs, I like the result better in RawTherapee much more than darktable. That’s not meant as a knock on darktable, but to say that RawTherapee has done an excellent job. I believe the scope of the tools are different, e.g. darktable has separate tools for black/white point and modules for a few other sliders present in RT’s exposure module.
I don’t disagree at all with anything you’ve said, I just wanted to highlight what stood out from each application as someone who uses both programs regularly… This probably means I’m master of neither. 
@haqthinh I have bounced between applications but since I primarily use Windows I tend to use RT more often. I suggest that you try to use both for a short while. Then observe which one you tend to open more often. Most likely what fits your groove is the correct choice. Once you figure that out, you can then aim for depth and complexity.
I assumed so too… I was just hoping to get a bit more context to fully appreciate the humour 
@paperdigits what are the reasons why you need to use both regularly? Are you like the hackerman who develops both? 
I use both. The main draw of Rawtherapee for me is Pentax pixelshift, simpler exposure tweaking, better highlight recovery and faster GUI zooming etc.
Darktable is better when dealing with lots of photos. Filter by tag across all my photos, nicer metadata UI. I get way better results with DT equalizer than RT wavelets. I also achieve better noise reduction and sharpening with DT. Darktable has perspective autocorrect which works, saves me a lot of time. The masking drawn and parametric is useful to.
I photograph mainly buildings and spaces and my family.
I am certainly not developing on either, I don’t possess those skills.
When I want to work on one image only, I generally use darktable.
When I have a batch of images, from a family event or part of what have you, I tend to use RawTherapee.
With the caviot that if I’m not happy with the results I’m getting in one application, then I pop into the other.
I also use both so I can be reasonably familiar with both, so I can help people here and elsewhere, so hopefully people find that of use.
I know it’s not the main comparson but how does photoflow compare to both? I just ask, even though it’s a young program, since it seems to take the best from both and possibly relevant in this thread. Also I have limited experience with any if these, so I’d be interested in opinions whether photoflow is the replacement, now or in the future, for both of these programs? Is these anything major that it’s missing?
Photoflow certainly looks promising, but it is still very young. The main advantage of photo flow is the non-destrucitve layers approach and non fixed asset pipeline. It is very powerful but currently lacks a lot of the tools RT and dt currently have.
For me, I prefer RT for how easily and precisely you can use curves and for the wider range of modules available. BUT, I’m totally in love with the availability of masks and the possibility of having multiple instances of the same module in Darktable. To the point that I’m almost exclusively using Datktable now - although I do miss RT’s lovely curves! 
If all I do is open an image and set the exposure module to ‘auto’ in both programs, I like the result better in darktable much more than RawTherapee. On Linux, recent builds of both. Auto exposure in RT produces flat, lifeless and bloodless pictures, at least with a Nikon. One time (two, three…) out of hundred RT gives a good result with auto settings. So use that with care and always compare the results of RT with the camera generated jpg. The last one is often much better and more pleasing to the eye.
I’ve never shot a jpg on my D750 
All of the things I’ve said in this thread are my own preferences and should be taken as such.
My snapshot camera, a YI M1, also shoots DNGs and I only batch process those, and I like the results from RT a lot more with auto settings. I tend to shoot a of things that lack good contrast, so maybe that’s it. There are probably too many variables to say for sure 
I haven’t looked at Darktable for a long time but concluded that for raw file development and surprisingly work on jpg’s RT is better and has got even better over the years I have been using it. From memory Darktables masking is essentially luminosity based. That can only do so much. RT probably uses the same technique in places but it’s hidden from the user. It’s not going to be that easy for a new user to make full use of all of it’s capabilities. DT is probably much the same.
In terms of packages a lot depends on how far you want to go with post processing. I sometimes spend a lot of time on a forum that is nearly 100% photoshop. If some one want’s to get into the sort of things that the more capable people on there do I feel that neither package on it’s own is suitable. Adding the GIMP for selective and layer work can help a lot with that aspect. It also surprising what simple layers and mask generated by brushes can do to shots and it’s not that hard to do. Usual advice to people doing that sort of thing for the first time is to be bold. Personally I feel the main problem with the GIMP is learning to use it. There are plenty of specific tutorials about but one area isn’t covered very well - layer modes. Tutorials will sometimes show them being used but I feel one that takes each of them and gives an idea of how they are intended to be used would be far more useful.
Personally I think Fotoxx is worth a look too. Open a decent raw file with it and it will give an image that can be worked on. If not right click it and edit it in RT first and then return to Fotoxx. There are a number of video’s on how to use it and the doc’s are pretty extensive. Linux only though. I found it via a review that also mention how lucky we Linux people are to have it available.
John
Your memory has failed you. darktable supports many more things to use as parametric masks than just luminosity, and it has done so right from the start when these masking features were introduced. Nowadays darktable also features powerful drawn masks that can be combined with the parametric ones.
My main takeaway from these types of questions (and answers) is that I’m seriously dropping the ball on community outreach and tutorials. 
I wonder if a series of short posts looking at specific things might help raise awareness of capabilities better. For instance, masking in each, or demosaicing, etc… If anything it might give a nice understanding of current capabilities (and we can revisit as necessary to stay current).
Sounds like a good project / blog spots
Disclaimer: I have always used RawTherapee even though I consider myself a beginner since it is an incredibly powerful software …
Since I am a Windows user and Darktable does not work on this platform I can only tell the differences based on some video tutorials I have watched on YouTube in the long past.
However, by taking a look on Gighub, I have noticed that Darktable is going to fill this gap in the future and will be available on Windows as well 
From what I have gathered, just out of curiosity, Darktable is much more similar to Lightroom, compared to RawTherapee, in that it is more feature complete.
For instance, with Darktable you have:
This being said with RawTherapee you have pretty much all these abovementioned features by simply adding to your workflow : Digikam
Of course, RawTherapee also sports some unique features: e.g. the pixel-shift module to handle RAW Pentax files.
BTW, as already mentioned in this thread, there is a new kid on the block: PhotoFlow
Thanks to his layers structure, it is already a very promising open source package.