If you loved The Batman/Superman Movie: World's Finest, try Superman: The Last Son of Krypton
A bridge between a film you've already seen and one most people haven't. Superman: The Last Son of Krypton has roughly 3.4× fewer votes than The Batman/Superman Movie: World's Finest — it's a deeper cut, not a mainstream recommendation. Here's what they share, and what the second one does that the first one doesn't.

The Batman/Superman Movie: World's Finest

Superman: The Last Son of Krypton
What they share
Theyboth carry the cozy, playful mood tags, and they sit in Action / Adventure / Animation / Family / Science Fiction / TV Movie territory. If that's the register that drew you to The Batman/Superman Movie: World's Finest, the second film will land in a comparable space — through a different lens.
What Superman: The Last Son of Krypton is
Here's a movie that understands the assignment. Mild-mannered Clark Kent uses his array of superpowers to become Superman. He then defends Earth. He does a pretty good job, all things considered.