Question: Any suggestions for an accurate Web Log analysis tool to generate reports on the IIS logs? We used WebTrends, but I don't feel it was accurate.

Answer: 
**SHORT ANSWER**: 

You are correct to question the results; log analysis is not adequate to report actual traffic.

**LONGER ANSWER**:

WebTrends is a great tool for what it delivers. But as a previous administrator of a WebTrends installation, I found that web logs are notoriously bad at capturing metrics of interest.

For instance, if there exists any caching in your web delivery stack (or on the consumers side-- \*I'm shaking my fist at **YOU, AOL**!), then your web logs are instantly non-reflective of your site's actual activity. This is because log analysis assumes that all user consumption will translate to an HTTP request back to the web server-- and thus having been recorded in the IIS logs. In the case of a cache, this would not be the case.

In the future if you want more reliable results, you ultimately need to ensure that there exists a way to bust any caching strategy. The obvious answer is dynamic content. But if you do not want to rewrite all of your content in such a fashion, just ensure your web traffic analysis uses a dynamic call.

WebTrends actually offers a solution to this problem, called SDC server. This is exactly what Google Analytics offers as well-- it's a javascript call back to the analysis server.

...I could go for days on this. If you want more specific information, comment back. ;)

***EDIT***: With WebTrends, specifically, it is quite important to configure session tracking beyond their default IP/userAgent configuration. If your web server assigns a session cookie, you will find this will increase your reliability; especially for differentiating between users which may sit behind the same NAT.
I have been using Summary, which is paid for software, for years, and love it. The cost of updates is getting to me, and paying for an update to just get user agent string updates out of the deal is getting bothersome. Not that there are not other fixes, I just tend to not need them.

Anyone care to share if they have used Summary compared to analog?