There really is just to much to decide. I doubt there's anyone who's seen every anime ever, which is what someone would need to do to make a judgement about something like this, especially because there are several bad enough to make the viewer's eyeballs melt or boring enough to induce comas.
My personal favorite anime is probably Tenshi no Tamago ("Angel's Egg"), which will likely never be released here because no one would buy it and the people who butchered it into part of "In the Aftermath" still own the rights. It's a deeply symbolic and extremely ambiguous art film directed by Mamoru Oshii with animation by Yoshitaka Amano. I has a uniquely beautiful visual aesthetic, almost no dialogue, and it's the kind of movie that you get something new out of every time you watch it because it can be interpreted in so many different ways.
I think that everyone can hopefully at least agree that MD Geist is, collectively, the second worst anime ever.