From a pressure perspective, 5CC leaves you with the least followup options and they tend to be predictable.
From 5CC, you can use:
-Special cancel
-6B
-Charge cancel
Whereas from 5B(B) for example you get access to more gatlings and mixups, including the charge cancel which makes 5BB > CC better. Heck from 5C you can even go into 6C.