Analytics for me has always, been at the core of my measurement toolkit an it would have to be a pretty amazing advancement made by someone else to make me move. Google Analytics is great out of the box, but when you start digging a little deeper, setting up goals and commerce, custom tracking elements, reports, exception rules it really start to come alive - sometimes hard to believe it's free for what you get.
That said I do leverage other tools when I need to dig even further on certain activities. Click Tale etc offer insight in ways that GA just can't. Their form analytics is a good example http://www.clicktale.com/product/form_analytics . There's also often a need to integrate other business metrics with online activity and for that I use more generic reporting tools.