I think it's too early to say considering how we don't know much about the movie itself at this point. If, like the teasers indicate, we do get some big Rider vs Sentai battle, then I guess Marvel vs DC is more adequate. Rider and Sentai might be owned by the same company, but they aren't different incarnation of the same concept (unlike JLA vs JSA - which is more like a standard Sentai Vs) nor do they have a history of interactions and conflicts (unlike the Marvel characters).
If we get a "Worlds colliding and fusing" story, with the heroes of each world fighting each other before teaming up against the main villain, then a proper comparison might actually be the Justice League vs Avengers mini series.