RAW Therapee

Not tried it yet as I don't have any RAW files on this PC at the moment but looking at the spec's:

Image post processing in 16 bit / channel mode
Most RAW files aren't 16bit but 12bit so does it change the bit depth to 16bit whilst you make your adjustments or keep it at it's native bit depth and then merely change the output to 16bit? Not that big a problem either way as all RAW editors do this on way or the other.

Exposure control in RGB space
An essential control

Auto exposure with adjustable clipping point / Exposure compensation / Shadow and highight compression / Contrast adjustment, curve editor
Nice

White balance adjustment in RGB space
An essential control

With in-camera, automatic and spot white balance options / Temperature/Green tint fine tuning
Good

Highlight Recovery
Nice feature to have but it'll be interesting to see how good it is. If highlights are blown than they simply havent been recorded so you can't recover them, if they've 'just' been overexposed than they can be recovered but many 'cheap' editors tend to go for a broad brush approach and alter too many highlights resulting in almost washed out look. Although to be fair even the best software will do this if used at extreme settings so there's still no substitute for getting it right in camera first.

Shadows/Highlights control in RGB space
Good, but this can end up looking like the Highlight recovery tool if it's not done well or used to heavily.

Basic Luminance curve tool to modify the luminance channel in CIELab color space
Useful

Brightness / Contrast adjustment, curve editor
Nice....If it works well. Too many editors don't have this but if you don't have something like Photoshop you need it to be in your RAW editor.

USM sharpening applied on the CIELab luminance channel
Cool. Luminance sharpening is often a better way of sharpening images than using a standard USM as in Photoshop

Classical USM parameters (Radius, Amount, Threshold) / Option to avoid noise amplification / Sharpening halo control
Cool. Nice to have this option as well.

Color shift control in CIELab color space
Not entirely sure what this is, does that mean you can only colour shift in Lab Colour or merely that if you work in Lab Colour you have this option?

Allows color shift by shifting the CIELab "a" and "b" channels
As above

Color booster applied on the CIELab "a" and "b" channels
As above but a useful feature

Amplifies color channels "a" and "b" together or separately / Avoids color overamplification in high chrominance areas / Option to avoid clipping caused by too high color boosting
As above

Luminance denoising algorithm applied on the CIELab luminance chanel
If this actually works than it'll be cool but I doubt it. Good denoising involves a lot more than applying gauzing blur to the luminance channel which is how I suspect this works

Edge sensitive method to preserve as much details as possible
As above

Color denoising tool applied on the CIELab "a" and "b" channels
As above, if it works cool but it'll never replace a dedicated denoise piece of software

Classical gaussian blur or edge sensitive bluring of the color channels
Naf way of doing it that rarely works well enough.

Fast switching between different postprocessing profiles
Useful

Image flipping horizontally or vertically, rotation by 90 degrees clockwise or counter clockwise
A standard control

Arbitrary image rotation (straightening tool)
Good but how does it do it? Does it require you to move the image manually which can be a bit hit and miss or can you draw a line on it like using the ruler tool in Photoshop and then it rotates according to that which is a great way of doing it and does it project a grid over the image so you can see when it's straight?

Simple lens distortion correction
Useful......if it works. So often these controls do virtually nothing, even in expensive 'pro' software.

Crop tool
Essential tool but does it project a rule of thirds grid over your photo?

Chromatic Aberration correction tool
Very nice......if it works. So often these controls do virtually nothing.

Change History with bookmarks to support before/after checking
A well thought out feature that could prove very useful

Output options:
Supported file formats: JPEG (8 bit), PNG (8 or 16 bit), TIFF (8 or 16 bit).
Standard formats but all that you should need. However does it let you specify different sizes/resolutions so that you can for example export a 16bit TIFF at 3024x2016 whilst exporting a jpeg at 70% compression at 800x533 at the same time?

EXIF data is preserved in JPEG output (except crw files)
Standard feature but good to have

Output directory and automatic file naming highly customizable
Standard feature but good to have

File browsing with thumbnails
Good.....if it stores the thumbnails and doesnt have to redraw them each time.