twest the enhance stats should be as accurate as you can get. It's including all requests, not filtering out bots or spam traffic like Google Analytics would do.
The "unique" value filters out known bots but a lot of bots disguise their user agent as a browser. Javascript analytics such as Google Analytics can detect this but there is no way a web log parser will be able to do this.
After filtering out bots, we take a hash of the user agent + IP to determine whether a visitor is a "unique". This isn't perfect but it's similar to the way other web log parsers function.
The Enhance traffic stats are better than GA for tracking periods of peak server load and for measuring comparative website traffic but for visitor tracking you're better off using something with a Javascript embed.