I recently tested these 3 products for myself and came to the following conclusions:
C17 gives the best overall image quality almost without exception. Greatest detail and lowest noise. I did run into a software bug, but tech support is very good.
DxO8 is close behind C17 when it supports your camera/lens combination. If your camera lens combo is not supported it is best not to use DxO for RAW processing.
LR4 is not too far behind, but is a definite 3rd given the above. However, I do have some older RAW files not supported by C1 or DxO and still value Adobe Camera Raw (whatever form) for doing a decent job with these files.
I make and sell prints of my work for a living and come from a large format background. I've owned/used C1, DxO, and Adobe CR for several/many years. C16 was a step behind in image quality, but C17 is the real deal
Image variables such as color rendering, etc. are too difficult to judge using default settings and all 3 programs have good adjustment tools