As a marketing consultant, I am often asked/hired/consulted with regards to implementing a web site traffic analysis package. I’ve pretty much used them all, with heavy emphasis and recent preference for Google Analytics. Though, I do find myself having to sell this product to executives a little more than other tools, but in the end, it’s never failed to deliver valuable insight.
Here’s a great web site that updates statistics on analytics packages on a regular basis to illustrate market share. I recommend referencing this site in any analytics presentation: