In this thread many people have indicated that they use log4net. I am a fan of TraceSources and would like to know why log4net is used.

Here is why I like trace sources:

• Pluggable listeners - XML, TextFile, Console, EventLog, roll your own
• Customisable trace switches (error, warning, info, verbose, start, end, custom)
• Customisable configuration
• The Logging Application Block is just a big set of TraceListeners
• Correlation of activities/scopes (e.g., associate all logs within an ASP.NET request with a given customer
• The Service Trace Viewer allows you to visualize events against these activities individually
• All of it is configurable in app.config/web.config.

Since the .NET framework internally uses TraceSources, it also gives me a consistent way of configuring tracing - with log4net, I have to configure log4net as well as TraceSources.

What does log4net give me that TraceSources don't (or that couldn't be done by writing a couple of custom TraceListeners)?