What is the best GIS software?

There is no "Best" GIS software, it depends on your needs, yous have to define what you want to do then choose the best "tool" that responds to your needs

ArcGIS desktop10.1

ESRI _ ARCGIS10

Arcmap10.1

MapInfo11.0

It depends :-)

ArcGIS Desktop10.2.1 the latest and best 

ESRI products are the best GIS software.

At present arcgis10

Esri software programs are the best as they  are known to be flexible and use friendly. Arc Map10.2, is the best and latest program.

Sadly, the truth is that Is the best for what  client WANT is ArcGIS, while the best for what clients NEED is (A map API, Database and a server side script "I use php").

 

Remember that "There is no short fit all" ;)