Daicon III:
It's endearing to know that the otaku in charge of that convention understood even then that the essence of anime is "cute gorl; also fetishistic referencing and remixing." I liked her design and I liked the ersatz monsters and mechanical stuff. It's not like I was expecting a story, so I wasn't really disappointed in any regard. If there's not enough here, it's just because they would go on to do bigger and better stuff as professionals. As a community, we should be and are glad that they did.
Daicon IV:
Everything that Daicon III was, but, like, more of it. And topping it in basically every way. Cute gorl? We have a cuter gorl. Fetishistic referencing? We have references to everything a 1980s otaku would have given a shit about. And we have it all in smoother animation, with great shot composition and a whole lot of frenetic energy. One of my favorite ELO songs backs it up perfectly. Almost 40 years later, this is still an absolute treat.