When comparing SmoothMoves vs Puppet2D, the Slant community recommends Puppet2D for most people. In the question“What are the best 2D animation tools for Unity?” Puppet2D is ranked 7th while SmoothMoves is ranked 8th. The most important reason people chose Puppet2D is:
Instead of having to change sprites to bend legs or other joints mesh deformation changes the mesh shape based on joint weights to bend and move.
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Pros

Pro PlayMaker integration
Developers echo17 provide Playmaker action scripts for SmoothMoves.

Pro Texture swapping and tinting at runtime
Animations can be re-skinned in several ways, entirely on the fly.
Pro Mesh Deformation
Instead of having to change sprites to bend legs or other joints mesh deformation changes the mesh shape based on joint weights to bend and move.

Pro Inverse Kinematic bones
Bones will move and rotate reacting to the position of the rest of the skeleton. The animator does not have to animate each part of a joint but rather have it follow realistically. Also can be used for ragdoll effects based on physics.
Pro Built on top of Unity’s animation system
Mecanim and state machines work natively since Puppet2D builds on top of Unity’s built in animation system.
Cons

Con Bone hierarchy is not collapsible
When working with a complex skeleton, the entire tree is always visible. There is no way to hide bones under their parents.

Con Unity Middleware
SmoothMoves is not a stand-alone application. It runs entirely within the Unity Editor, and is not compatible with other engines.

Con Forced editor scaling causes problems
Puppet2D adjust the scaling of bones in the editor for display purposes, which results in unintended behavior if other objects use a bone as a parent.
