Scripted movement is easier for movements that can be described as a simple algorithm (the simplest being moving in a straight line at a fixed pace). Scripted movement is prohibitively hard for something as complex as realistic human and animal movement.
Animated movement is easier for complex maneuvers that cannot be easily described via an algorithm. You set the keyframes for position and rotation and let Unity fill in the gaps for you. Creating an animation is a bit laborious, though, hence scripts being easier for simple movements.
Another thing to note is that it is easy to adjust a movement script to work for any given start and end point, but it is harder to do the same for an animation (though still possible, I think).
2.This has the advantage of allowing more specific control, but it's generally difficult to create more complex moving paths.