I am new to GIS application world. I would like to ask what are the other alternatives to UMN MapServer in the market preferably open source?
Geoserver probably is the most known option among the open-source feature server applications. However, I personally use MapServer.
Here you can check some info about both applications:
To answer your second question (about commercial GIS apps), the "Mercedes Benz" of the GIS applications is ArcGis (based on some lists such as http://www.gisdoctor.com/site/gis-help/commercial-gis-software/).
However, I think you can achieve lot of GIS capabilities with two open-source software projects, these are:
Wikipedia is a good source to search for more open-source and commercial applications: http://en.wikipedia.org/wiki/List_of_geographic_information_systems_software
Hope this helps,
MapGuide opensource is, like MapServer, a cartographic engine server-side.