Generally we will be considering google analytics to check the data information of a particular site... But some other analytics were also present like piwik, sas etc.. Can anyone clarify on this...
google provides enterprise class analytics for free. it allows many other features like custom variable tracking , even tracking and so on. but only problem with it is, the delay in update of data. it take 12+ hours to update the analytics data. services like get clicky provide instant information. but they are mainly paid version .
In free services Google is the best one..I have been using it for ling time..more ever it will bot give exact but it's the best one compare to others, you can use stat counter also then check the difference..
It might not be totally accurate on any individual day but over time, the variances cancel themselves out over the long term. I wouldn't worry about the odd spurious result here and there.
The most reliable analytics service at no cost is very good for any kind of site.. it gives the quality data and help to grow by working on that...Most reliable tracking of websites....