I've watched it on Main Street and in Liberty Square by Country Bear Jamboree. Although I normally LOVE watching parades on Main Street, seeing the Halloween parade in Liberty Square was better because it has better lighting. All video and photos of the Headless Horseman came out much better in Liberty Square then Main Street.
I watched Hallowishes where I normally watch WIshes, right in front of the Castle...very close to it; too close to it, IMHO. I couldn't see half of them as the castle blocked their view. If I had only been a little further back, maybe at the beginning of Main Street, near Casey's Corner, I could have seen it much better. But I would want to be in front of the Castle though because of the images projected onto the Castle.