General animated image questions

I've got an animated image I'm planning to upload, and it's available in two different formats: the original gif and an mp4 version made with a converter. As I stared at the upload screen, several questions were raised in my mind, and I don't know if they've been answered, or if there's a central place where they're all answered, because finding things in this forum is a nightmare. Therefore, apologies if these have been asked already

0. Is there an official/generally accepted tier list or order of preference/desirability when it comes to animated image formats (gif, webm, mp4, ugoira, flash, animated png, etc. ...)?
1. If not, shouldn't there be one?
2. Or, instead, should I only upload the original because it's the original?
3. Or upload both for completeness' sake?
4. Or what if the creator of the image themselves provided it in multiple formats?

Third-party conversions are in general not allowed when the original is available.

In the case where the creator makes both available (such with twitter mp4 and pixiv ugoiras) often both are uploaded, but there's no rule on which one to prefer. You have to use your eyes and see which one has the worst artifacts (typically pixiv/gif versions are superior to twitter mp4s because of compression artifacts).

Huh. that's pretty simple and reasonable. All right, this clears things up.

Thanks for the answer!