Although *I* feel Vegas is the leader in MY world, I can't say it is overall. I posed the software question to the panel of director editors at our latest "48 hour film project" fest and only one of sixteen used Vegas for editing. FCP dominated, followed by a number of Premier or "adobe" products.
I trialed everything and Vegas came out on top for me.
I dunno... I watch my buddy use FCP, and have to hold back my comments... "man, I can do they 4 times faster in vegas.... " and "you have to RENDER FIRST just to SEE what that effect does????" He was amazed I was viewing and editing raw footage with a live preview on my laptop. How could you edit without that???
When you are competing in an industry that is predominantly Mac based and you don't run on a Mac it's kind of a non-starter. Avid, Premiere, and of course Final Cut Pro all run on a Mac. Vegas does not. :(
Video production is an ecosystem with a pipeline of products and you can't change any component of that pipeline if it doesn't run in the same ecosystem.