I'll just throw this out there...
SolidWorks anyone? its a huge part of the cad market and its used all over the place... not to mention its parametric, handles odd-shaped surfaces well, and if your making parts that are going to be moulded it takes very little time to make moulds.
Also, unlike inventor, when you make a gearbox or put belts on things it's not necessary to define any ratios between rotating parts of an assembly... solidworks just knows the gears move because of the individual teeth colliding, then throw in that it does gravity in assemblies, and has both individual part stress analysis as well as whole assembly stress analysis... don't about you but thats just cool!
-Q