While not being able to answer your question directly, we ere there on Halloween night last year which was "sold out". Never even dealt with crowds. We walked onto all the attractions except for those in Fantasyland and figured we would do those another day. It was great to be able to walk on to any of the "mountains" and go!
So even if people tell you it will be jammed (which they told us) it can still be great. I would do whichever day works best for your schedule.