So which effect would you prefer
You also need to keep in mind users that suffer from motion sickness, and have to take them into account (essential nowadays for Search Engine Accessibility factors) which is fairly straight forwards deepending on the parallax effect you want
For the moment, probably the one that is easier to implement and leaves the bowels of my users intact...
Astronomy site: http://www.astronomy.artinso.com
Musical events: http://www.orphelion-ensemble.com
ED V4, SD V5