3D and 2D Tools

The best tools on my concept are:

3D

• Blender(Freeware, Open Source and Cross Platform) http://www.blender.org/
  
• 3DS MAX http://www.autodesk.com
• ZBrush http://www.pixologic.com

2D

• GIMP(Freeware, Open Source and Cross Platform) http://www.gimp.org/
  
• Adobe Photoshop http://www.adobe.com

Professionals often use commercial softwares like 3DS MAX and Adobe Photoshop, but you will not belive that with a little effort you can make almost same work with Blender and GIMP.