When comparing GAF:Flash to Unity vs TexturePacker, the Slant community recommends TexturePacker for most people. In the question“What are the best tools to create sprite atlases for Unity 2D?” TexturePacker is ranked 1st while GAF:Flash to Unity is ranked 3rd. The most important reason people chose TexturePacker is:
Drag and drop sprites onto the canvas, change the settings, then output.
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Pros
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.
Pro Simple Interface
Drag and drop sprites onto the canvas, change the settings, then output.

Pro Multiple Atlas Output Formats for Unity
There are three different outputs for Unity to read the atlas; JSON, Texture2D, and 2D Toolkit.
Cons
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.
Con Pure functionality in the free version, you can't even set margins
The full price is too high for such a simple app.

Con No direct integration
TexturePacker is an external third party application with no Unity Inspector interface.
