pre-2000 for me. I prefer OVA's and movies to long running series, just in terms of quality and also the fact that a 26 episode series can run out of steam and lose its way.
Having said that, some OVA series are too short. For example, Please Save My Earth is 6 30min episodes, and while that is enough for the story it conveys, it condenses a huge part of the original manga into a few montage minutes at the end of part 6. Both the Battle Angel Alita and Tokyo Babylon OVA's are great, but as they are based on long running manga, it seems a bit of a waste to only have short OVA's that don't bring the story to a definitive end.
I think the animation quality argument is a bit redundant - Akira, GitS, Macross Plus, Ninja Scroll, X Movie etc. all have amazing animation, and not all the releases nowadays are expertly animated. Most rely on huge amounts of CGI that lack the charm and presence of traditional cel animation.