CU-Boulder does not prefer one application over the other and all students will be reviewed in the order their application file is completed (submitted application and required documents received and official) regardless of which application is used. The most important thing is to choose ONLY ONE application and use ONLY that application all the way through to submission. If you submit both applications, you will delay your admission decision.
Note: The Common Application is only available for first time freshmen. Transfer students can only complete the CU-Boulder Application.