We started with a 426.6 MiB file. Here are the qualifying seven:
Preferring quality, the winner is:
Animation, 16-bit color, High quality.
No, really. You read that correctly. 16-bit color.
Remember the file sizes:
Animation 16-bit high is just over half of JPEG-2000 medium's size, and all three of these look about the same. So Animation 16-bit high wins.
The next four, in continued declining order of quality, are:
If you absolutely must serve up a small file, then H.264 medium is the way to go.