When comparing TexturePacker vs Filter Forge, the Slant community recommends TexturePacker for most people. In the question“What are the best sources for textures for game development?” TexturePacker is ranked 1st while Filter Forge 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 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.
Pro Not only a Photoshop plugin, has a lot of other hosts
Pro Several filters
Filter Forge includes a lot of filters and each of them has several presets. Filters are grouped into different categories (Organic, Patterns, Creative, Distortions, Photo, etc...) so it's easy to locate them.
Pro Large online library of filters
The website has thousands of filters available for download. This is the only thing that makes the basic edition feasible.
Pro Standalone application or PhotoShop plugin
Filter Forge can be used as both a standalone application and as a plugin for PhotoShop.
Cons
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.
Con Slow development cycle
New versions come fast enough, but for example, the beta version of 7 doesn't have a lot that 4 didn't have.
Con No free tier
Filter Forge is not free. The basic edition (cheapest one) is $149. It does go on sale regularly though for around $30.
Con Hefty price tag
Its $399 for the professional version, whereas a big competitor used by large studios is only $149.
