Choosing the best video editing software means first evaluating your needs and considering what features you need.
For beginners and video hobbyists, I think that the best video editing software is whatever comes free with your computer - Movie Maker for PCs and iMovie for Macs. Both of these video editing programs are priced right, and offer tools and features that allow you a lot of room to learn and be creative with your video editing.
More advanced editors may want to move beyond the constraints of the free programs. For them, the best video editing software is probably something in the $100 range. Many of these programs come with HD capabilities, DVD burning software, and advanced tools and effects that let you do more as a video editor.
The best video editing software for professionals is going to be pricier. Most professional video editing software programs - like Avid, Adobe Premiere, and Final Cut Pro - offer similar features and tools. You'll want to choose the program that will be compatible with your computer and with the other software used by you and your colleagues.