Modo has been getting a lot of press lately. I has been praised as an innovative new approach to 3d. Perhaps the most intriguing feature is the ability to do parametric painting right in your viewport. The program also claims to be able to instantly update renders as you paint on them in 3d with a constantly rendering viewport. Besides these interesting abilities, Modo also claims to be very user friendly, and very fast! It's worth checking out. Download a free trial here. 30 day full trial version (the full version is only $895!).