The Qorivva products, a Power architecture, are used widely in the automotive industry. It has specialized peripherals such as CAN and LIN. Automotive products are built tough, to high industry standards.
The Kinetis products, ARM M4 architecture, are widely used. You will find it in lots of everyday devices and industrial automation (such as robotics). It can support a lot of consumer peripherals such as USB, WiFi, and Graphical Displays.
Which platform is more powerful or easy to use?
Both supported processors are powerful 32 bit microcontrollers with similar software peripherals. Take an hour or two to research the evaluation boards on the Freescale sites and their underlying technologies. Think through the design and implementation process of connecting various components like the motor, battery and servo, to the evaluation board. The Tower System provides a modular prototyping platform, and the TRK evaluation board has many features.
What level of support does a technology have?
For the Cup Challenge, you may use any Freescale microcontroller. There are reference designs here on the wiki and TONS of code and examples on the Freescale site. Students should speak with their professor, and check out their respective documentation and software examples to make a choice. Having on campus support is invaluable in this case. There are online communities for the respective technologies as well. Research which technologies are have more active user communities which best complement the teams design approach? Obviously the Freescale Cup Wiki itself is a resource, and provides details on how to use two different microcontrollers - so it might be best to limit choices to one of these two supported platforms.