Yeh, you saw the title. Which one truly is superior?
I haven't set eyes on a PS3 yet, so I dunno about that, but the XBOX360 uses Dolby Digital (and sometimes PLII), and the Wii uses PL/PLII.
As far as I understand, Digital uses 5 seperate physical channels to deliver the 5.1 sound, which can yield more direct surround sound, and more accurately. The problem with Digital is, I cannot seem to find any devices anywhere, to support this standard. So far, the only source of true dolby digital sound I can find is an HDMI cable. Anyone wanting to harness Dolby Digital will have a hard time finding sufficient support.
Now, Dolby Pro Logic (or Pro Logic II) is a surround sound method where 5 channels of sound are encoded using spatializing effects in just 2 cables (channels). This is the method both the GC and Wii have used, and this method appears to be far more common as it's what most DVDs and DVD players use.
The thing is... why is the emulated method more supported then the true method of surround sound? Don't get me wrong, PLII still delivers fantastic sound comparable to Digital itself, but I still find it odd that Digital has little support.