Playing 3GP Files from Smartphone
Very fast and easy to learn.
More advanced than Paint.NET, but has a steeper learning curve.
Audio & Video Editing
AVS4YOU is great for people that need multiple tools in one affordable package, including photo, audio, and video editing. Very good deal considering the breadth of media editing that is supported, and the number of file format it works for.
Movavi Video Suite, $59.95+
This is a great video editing suite, especially for people that need to produce screen casts.
Home & Office
Microsoft Office 365, $130+