Without a doubt the statistics provided by your website host, within your website Control Panel.
Third Party applications, such as Google Analytics, merely "read" the logfile information they are allowed access to.
Terry and I have used several Third Party applications, and in our opinion Statcounter is the best. it provides results consistent with the AwStats which is what our service provider uses.
The reason we use Third Party applications is because: (1) It keeps our clients out of the Control Panel, where they can break things, and (2) because the awStats interface is just a tad difficult to absorb for non-geeks.
Client feedback we have had about StatCounter is very positive.