Well, this could be an huge discussion, I will try to give you some quick points in a few words.
You may compare the software in your list from tree points of view:
Here the already suggested benchmark will be your best friend, at least for WMS
2) Services offered
Generally you may consider which services are offered from the software: this services may be compliant to OGC web standards (WMS, WFS, WCS, WPS, SOS, OCS...) or not.
GeoServer natively offers WMS, WCS and WFS (for the last two it is the reference implementation). It can also give support for WPS with an extension.
MapServer offers WMS, WFS, WCS and SOS, but with respect to GeoServer it lacks the transactional features for WFS (WFS-T). With respect to GeoServer in many case it has less architecture overhead (as it works with Apache httpd) and has a huge list of supported data format via GDAL/OGR. It lacks a nice admin web interface (like in GeoServer), but mapfiles can be easy modified and customized via shell or mapscript API.
Mapnik is a powerfull library that can be used as a WMS (and according to the last benchmarks at FOSS4G 2010 its performance are impressive).
There are other well knows softwares that provide implementations for WPS (pyWPS, ZooProject, 52n WPS), for OCS (GeoNetwork) and still other ones.
If you consider MapFish then you would possibly need to add the list GeoDjango and FeatureServer that offers not standard implementation of GIS web services.
GeoNode is a cool attempt to web2.0fy a SDI (ie with tag and social stuff).
Also give a look to the new kid on the block: TileMill, that is mainly based on Mapnik, and it is build on the node.js framework
GeoServer and GeoNetwork are Java based (so they require a servlet engine like Tomcat).
MapServer and Mapnik are C based, and they run well on Apache httpd.
All the other softwares are mainly based on Python using different frameworks: MapFish use Pylons, GeoDjango and GeoNode uses Django, FeatureServer and pyWPS are in pure Python. They can all run in httpd via modPython or WSGI or as CGI.
Note that almost all of this software is based on the ubiquos GDAL library (often even found in proprietary software).