Criterion is easily the best version. I have every single version of Robocop in every format, and I've compared the video and audio more times than I can remember, and the Criterion is the one I always go back to.
There is another interesting point about the Criterion, where the audio has some differences that are not heard in other audio mixes. Someone did a comparison on a website somewhere - I will try to find it if anyone is interested. It had things like different gun sounds etc.