MapInfo Professional by Precisely (formerly Pitney Bowes) specializes in location intelligence, business analytics, and geocoding services.
OpenJUMP GIS is good at the basics. It started as a tool for data conflation. Then, it grew into a modest size open source project.
Global Mapper by Blue Marble is a 64-bit GIS application. It has a powerful, intuitive interface, especially with LiDAR and terrain mapping.
ILWIS is free (GNU license) for users around the world for GIS and remote sensing needs. Here are some of the neat features and developments.
While not necessarily your prototype GIS package, GeoDa carries exciting analytical & visualization tools in industries like economics, health & real estate
Maptitude prides itself as an affordable one-stop shop GIS on the market with a low learning curve. It shines in business and transportation.
Companies, government, and the military embrace GeoMedia because of its solution-driven approach and its ability to extract actionable information.
Golden Software MapViewer emphasizes scientific data mapping, modeling, and analysis. But it can also work with various thematic maps.
GRASS GIS (Geographic Resources Analysis Support System) is one of the oldest public domain GIS software in existence – over 30 years old.
Whitebox GAT (Geospatial Analysis Toolbox) specializes in terrain analysis. But you can do processes like LiDAR and hydrology analysis.