And of course the basic problem of what is meant by 'hold up well', right?

I mean, both Gatchaman and Mazinger Z hold up well in terms of storytelling, concept and so on, but if one gets their panties in a bunch over 'old' looking animation then they're abject trainwrecks of mass failure.

Meanwhile modern stuff in many cases seems to suffer the opposite- cutting edge animation yet completely lacking in story, concept, imagination...