Looking at all these 100% crops, I must say that I can't tell a thing, except that Raw Therapee has substantially more contrast — to the point of blowing out the highlights; and Capture one has more contrast than Silkypix, which has more than Raw Developer, if I'm not mistaken; and Lightroom seems to have less contrast than Raw Developer. As for artifacts, diagonal patters and grain, I can't get a sense what is being shown here. Can you mark up some of these samples to point what you are talking about?
I would have thought that at the point of RAW development one would want the best rendition of detail and for contrast to be kept from being excessive, since one would want to make contrast adjustments and do selective burning and dodging in subsequent processing. In this sense, and from these samples alone, I would think that Lightroom, Raw Developer and Silkypix are better than Raw Threrapee and C1.
In my general experience, it seems to me that Raw Developer gives the best rendition and excellent sharpening, noise suppression, as well as beautiful B&W conversion. Silkypix is also very hood, and often gives good highlight detail and gradation. Silkypix has very good tools and controls. However, I have been using LightZone for RAW conversion because of its excellent post-processing tools, which compensate for it's less exquisite raw conversion, and allow me to work in only one piece of software, without having to save and archive an extra, intermediary, in addition to the original RAW file and the final TIFF file. Hence, if I used Raw Developer or Silkypix, I would have to keep the original RAW file, the converted TIFF file put out by Raw Developer or Silkypix, as well as the final TIFF file, containing the Lightzone adjustments.
In my case I run that final LightZone file through Photoshop for mild output sharpening with PK Sharpener and for coversion to grayscale, to which I then assign a gamma of 2.2 for printing with ImagePrint.
—Mitch/Bangkok
http://www.flickr.com/photos/10268776@N00/