Clicky Web Analytics is a wonderful tracking script that is easily comparable to Google Analytics. According to Clicky, there is no comparison between their premium product and Google Analytics. From a more objective viewpoints, where Clicky stands apart from Google Analytics is real-time tracking. Google doesn’t do real-time tracking. Not that it’s incredibly useful compared to examining the data after the fact, but when you have new content that day it’s good to see what kind of traffic it’s getting.
As with most services on the Internet, Clicky is free, up to a point. If you want to manage more than one site in your account or want to show off some real impressive heatmaps you need to upgrade.
Easy to install, good support for multiple platforms of CMS and mobile devices.
Frankly, I run both on any website that is worth running analytics on. Clicky Web Statistics will show you data that is a little different than what Google Analytics will get you. If you use these two tools in conjunction with Google Webmaster Tools and Bing Webmaster Tools you will be collecting some really useful information on how to improve your keyword impressions and rankings.