If you want the closest to what the camera actually took, you could try dcraw. In Windows it is used command-line in All programs/Accessories/Command Prompt. There are batch commands available in the Windows Command Prompt environment to process a number of files one after the other.
dcraw offers various algorithms for demosaicing. PTLens will remove distortion and one's photo editor of choice will adjust color, saturation, etc.. dcraw does do some highlight recovery. If I remember correctly, it won't process RAW files that don't use the standard Bayer pattern.
My experience is that the combination of dcraw, PTLens and one's preferred photo editor will produce excellent results.
This method is best used with small numbers of files, not hundreds at one time.
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