I loved Theatre of Magic's innovative use of magnets both in the trunk and in the magic ring. And the trunk in general - having 3 different mechanisms in one point of play was pretty cool.
Jungle Lord's (and maybe Hobbit?) use of drop targets that set and reset in various configurations is a fun little mini challenge.
And some of the early Bally (eg Centaur) have these super light wire gates that allow you to nudge yourself from the outlane to the inlane, if you're good at nudging, and it's a pretty satisfying thing to do.