Every era has some aspects I like, but I'm definitely partial to the 80's palette and aesthetic. I've been watching City Hunter lately and there's just a depth and feel to the colors in this era that modern anime doesn't reach.
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I'm also a bigger fan of the average character design from this era compared to the late 90s - 2020's. More human looking faces and hair. Some 90's and 00's stuff in particular had a angular (think yugioh or code geass) style that I tend to dislike. Higher budgets also led to nicer animation in the past, and some more recent trends like CG crowds or entirely CG anime often look like garbage. There's exceptions to every rule though, for example Houseki no Kuni is CG anime done very nicely:
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And more experimental styles can lead to appealing visuals in any era:
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