I feel like the most viable anime and manga franchises in this regard are those which are more... archetypal, I guess. Ie, where they're popularly known for their general concepts, rather than through having a strict, core narrative.
Example: Mazinger Z. Next to no-one actually looks to the original manga in terms of the 'core Mazinger canon', and even diehards would be hard pressed to remember every episode of the original series. Any team working on such an adaptation would be at liberty to do what they want so long as they maintained the basic premise. That being a young man inheriting his grandfather's legacy (a giant robot) and having to decide what precisely he wants to do with its awesome power (to be god or the devil, etc). Considering how well the world latched onto the character of Spider-Man and his whole 'with great power comes great responsibility' schtick in film form, there's clear precedent for bringing that sort of story to the big screen. Plus, any tropes too particular for wider audience tastes could be eased down, because they aren't visually core to the franchise.
From a production point of view, the nature of the franchise's storytelling would actually permit being careful with the budget, and save the big money for when the creators really need the special effects. See, while Mazinger Z is supposed to be a nigh-indestructible fortress that spends its time onscreen punching lesser robots into oblivion, that is exactly why a number of the main villain's plots (said villain going by Doctor Hell btw) revolve around killing the main hero before he can get in the damned thing. So you can have more affordable, low-key action sequences to go alongside the much more demanding robot fights, where the hero's relative vulnerability would maintain tension. Plus, Doctor Hell's not the sort of villain who needs to be entirely defeated in order for the story to resolve itself - thus a film could climax on taking out his latest and baddest machine, setting his plans back until the sequel.
In essence, take the Marvel approach with this, and it could work.