1. NGUI– as Unity GUI is not that great and Unity 4.6 is still no there you should have a frameworks to make good and robust GUIs. NGUI has evolved greatly since it was released and I can tell that I am a big fan of this framework.
Great alternatives: Daikon Forge GUI, Autodesk Scaleform (cool, expensive and complex)Verdict: MUST HAVE It may be not very intuitive at first but support, documentation and community are awesome. It allows you to implement GUI of almost any complexity.
2. uTomate – this one is my favourite. It allows you to automate almost every process in Unity. In my case it allows to make 10 builds for different platforms in one button click. Tool is also extensible. First thing when you start a production project – buy this one, it is worth every penny spent on it.
3. SmoothMoves – despite having some minor drawbacks this asset will help you to animate easily. Especially useful when you need to animate 2D Characters. It provides really convenient editor. Big plus – integration with Playmaker.
SmoothMoves Animation Editor
Purpose: 2D Skeletal animation Tool. Great Alternatives: Puppet2D Verdict: Useful when using skeletal 2D animations
4. Editor Console Pro– the default console if very inconvenient – no filtering, no coloring, almost nothing. So this one is a huge time saver – it provides a highly configurable console with all the info you need.
Verdict: MUST HAVE for medium and large projects.
5. Playmaker– one of the most famous and widely used assets from the Assets Store. Why? Because it is awesome. It’s a visual scripting editor which consists of state machines and events. It can be used to write a complete game without a single line of code or it can be easily integrated into existing project to simplify some routine work.
Great Alternatives: uScript Visual Scripting Tool
Verdict: Situational but highly recommended for projects with state machines.
6. SoundManagerPro 3 – A sound manager that deals with almost everything related to managing music and sounds. Big plus – integration with NGUI and Playmaker.
Verdict: Situational but highly recommended for projects with complex audio solution.
7. iOS Native and Android Native – the simplest and the best documented assets that provide integration with all iOS and Android features you can ever need. The support is great and fast. Absolutely must have for seamless iOS and Android integration.
Verdict: Situational but highly recommended for projects with iOS and Android Native feature. Even though there are lot’s of alternatives these two will save you lots time.