According to the Vol.26 issue of 3D World , the most popular 3D software is 3ds max with approximately 185000 users around the world while Softimage users is only 15,000 and Cinema 4D users is 62000. This magazine also picks Maya, Softimage, 3ds max, Lightwave 3D, Houdini and Cinema 4D (not in any particular order) as the best 6 3D softwares todays.
Best Overall : Maya
Best for effects : Houdini
Best for games : 3ds max
Best for value : Cinema 4D
Best for films: Softimage
There are still lots of information in that magazine that I misses out. For more information, see Vol. 26 of 3D World.