When comparing SmoothMoves vs GAF:Flash to Unity, the Slant community recommends SmoothMoves for most people. In the question“What are the best 2D animation tools for Unity?” SmoothMoves is ranked 8th while GAF:Flash to Unity is ranked 9th. The most important reason people chose SmoothMoves is:
Developers echo17 provide Playmaker action scripts for SmoothMoves.
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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 Can convert 99% of what can be done in Flash
GAF supports such Flash features as:
Masks support;
Filters support;
No limitations on timeline;
Conversion of shape tweens;
Frame labels.
Pro No need to use large Sprite Sheets
With GAF converter you get a highly optimized texture atlas and a config file. You don't need to take trouble over cumbersome sprite sheets. You can easily modify an already working in Unity animation and play around with the animations parts whenever you need.
Pro Alows using Flash animations in Unity
You can convert Flash animations directly in Unity with the help of plug-in. The converted .gaf file consists of a texturte atlas and a binary config.
Pro Supports different frameworks
Full playback API supported in Unity3d, Cocos2d-x, Cocos2d, Starling.
Pro Light, fast, and optimised
GAF is lightweight and fast in a project.
Pro Uses dynamic text
GAF can use dynamic text in animation on some platforms.
Pro Can customize sprite animation
GAF can swap a sprite with another.
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 Sound support available only in Premium version
GAF Converter supports sound but only in the Premium version.

Con Doesn't support sounds
GAF does not support importing audio along with Flash animations.
