If you loved Kamen Rider W Returns: Kamen Rider Accel, try Kamen Rider x Kamen Rider Fourze & OOO Movie Wars Mega Max
A bridge between a film you've already seen and one most people haven't. Kamen Rider x Kamen Rider Fourze & OOO Movie Wars Mega Max has roughly 14.4× fewer votes than Kamen Rider W Returns: Kamen Rider Accel — 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.

Kamen Rider W Returns: Kamen Rider Accel

Kamen Rider x Kamen Rider Fourze & OOO Movie Wars Mega Max
What they share
Both films are directed by Koichi Sakamoto, and they both carry the playful mood tag, and they sit in Action / Adventure / Science Fiction territory. If that's the register that drew you to Kamen Rider W Returns: Kamen Rider Accel, the second film will land in a comparable space — through a different lens.
What Kamen Rider x Kamen Rider Fourze & OOO Movie Wars Mega Max is
You patrol a city under crossover assault when the oldest Riders crash the party. Forced into uneasy teams the heroes face an enemy only the first seven can unlock. The director folds five timelines into one spectacle. You stand in a superhero stadium of comic precision.