It depends on what you plan on doing.
If you plan on a career as an editor, looking for work in episodic television and films, Avid and Final Cut are two programs you should get to know. Those parts of the industry are dominated by those two players right now.
If you want to edit your own movies and don't really care what the industry is doing, there are options.
I use Adobe Premiere Pro to do broadcast and HD, as well as 2K and motion RAW work right now (RED and SI2K are the two most popular RAW cameras at the moment...when I started with the SI2K, only PPro/CineForm could handle motion RAW...and only CineForm allows me to change the demosaic on the edit timeline-very handy). It works just fine and since I do a lot of compositing and effects work, the interaction between AE, Photoshop, and PPro are a timesaver.
Edius is very fast, but geared more toward news and event work...less frame size flexibility, etc than many other options. Vegas is a tool that has rabid followers who can make the program sing and those who just don't get the interface.
Since we all work differently and in different parts of the industry, some need to conform to what the industry seems to use most frequently, and others of us can just simply use what works best for us...
As I said, it depends on what your chosen direction is...
