If you read the source of both and spend 5 minutes on the issues of each and you will see that GSAP is a dated turd with more layers of cruft than photoshop and they still can’t do ESM or Typescript right even though they charge money for important features.

AnimeJS is S-tier, up there with Pixi in quality, albeit smaller scope. V3 was a bit rough but v4 has been baking for a long time.

The performance, code quality, ease of use, size, everything is worse in GSAP.