Avid is industry standard with FCP taking a close second, it seems. I'm recently in the midst of switching NLEs from Premiere to Vegas 4.0c. Now back in the day I used to argue "What can FCP do that Premiere can't?!" but if it's anywhere as powerfull as Vegas I've already answered my own question.
Now how about FCP and Avid vs Vegas. Is there anything these NLEs can do that Vegas can't. I feel sorta like I did when I thought Premiere was the end-all-be-all. I don't want to be as ignorant as I once was and think the NLE I personally use is the "best". So if anyone out there has experience with both or all 3 please post. I'd like to know why FCP has such a large following compared to Vegas's smaller yet enthusiastic following.

The one thing that Avid Xpress has that Vegas and FCP doesn't is the ability to integrate smoothly with other Avids and upstream projects to larger Avid systems. That can be very important or not, depending on how you work. Avid also has the Avid interface which will be familiar to other Avid users and is loved or hated depending on who you ask.

FCP has been out there a while, only runs on Apples, which has a certain cache for some people (the exaulted elite, not the rest of the great unwashed with PCs), and unlike Premiere, has been under constant development to make it better and more full featured. It is a very good editor.

Vegas on the other hand is a great program with a really stupid name developed by a company that wrote great software but was an absolute disaster at marketing. (One can only hope that Sony does a better job. They could hardly do worse.) Vegas's entire following seems to have grown by word of mouth.

Also up until Vegas 4.0 many folks who liked Vegas thought that it wasn't quite ready for "prime time". Now with new project management tools, good color correction and the ability to edit 24p and HD, that might be changing. Only time will tell.