I think it boils down to personal preference, and more importantly specific use case.
I don't know whether AnimatedSprite2D is more optimized.
But If you are comfortable with AnimatedSprite, and you don't need any of the other AnimationPlayer superpowers, just use that.
But I really like the AnimationPlayer. It can simply do more than just animating sprites.
Any property, as far as I know, can be animated using AnimationPlayer. Position, Scale, Rotation Color, Visibility, other booleans, and setting different textures, too.
And that's only scratching the surface.
Heck, you can even call methods !! Which brings more power and depth for the tool.