I have been using Adobe Camera Raw.
It is not perfect. It continues to improve, however.
The others are not perfect, either. Adobe watches their market and incorporates popular features from other RAW converters within an upgrade or two (and appears to be more willing to do so, than the competitors).
The camera profiles in ACR are so-so. I would say that's the biggest weakness relative to C1 or the latest release of RSP. You can tweak them for your particular camera easily enough if you own a Macbeth CC Card.
I do not let the RAW converter sharpen or remove noise. I prefer NeatImage Pro+ for noise removal. I use my own sharpening scripts for sharpening. So those are features I do not need in a RAW converter.
I do use ACR II to remove color casts in most cases and adjust the dynamic range.
I used to allow ACR to adjust nothing except white balance. I prefered adjustment layers for adjusting dynamic range, etc. But I can start off easily enough reworking an image in ACR II, and there are advantages to adjusting exposure, etc. prior to aplying a gamma curve.
I do not feel the need to have a bunch of RAW converted TIFFs cluttering up my harddrive. I like how ACR integrates right inside Adobe Bridge and opens my images right inside Photoshop.