If you loved 009-1: The End of the Beginning, try Ultraman Ginga S the Movie: Showdown! The 10 Ultra Warriors!
A bridge between a film you've already seen and one most people haven't. Ultraman Ginga S the Movie: Showdown! The 10 Ultra Warriors! has roughly 3.4× fewer votes than 009-1: The End of the Beginning — 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.
You already loved

009-1: The End of the Beginning
→
Try this next

Ultraman Ginga S the Movie: Showdown! The 10 Ultra Warriors!
What they share
Both films are directed by Koichi Sakamoto, and they sit in Action / Science Fiction territory. If that's the register that drew you to 009-1: The End of the Beginning, the second film will land in a comparable space — through a different lens.
What Ultraman Ginga S the Movie: Showdown! The 10 Ultra Warriors! is
You fight alongside Ultraman across the galaxy, but then a dark force traps them. The director Koichi Sakamoto brings an epic battle to life.