Candlelight Processional would be at the top of my list, now thru end of December. Would be hard to see it without a dining package unless you are willing to wait for hours.
While I love Fantasmic, I don't think I'd upgrade to a dining package to see it, I'd just wait in line (imo).
Hoop Dee Doo review is fun once, although I don't know that I'd need to pay to see it a second time.
I've been reading that a lot of the fireworks/harmonious dining packages, the viewing areas are not necessarily premium views, so take that into consideration when buying the package.