My last webhost gave me a WHM account with unlimited CPanel accounts. My first gave me only five which could host just one domain each.

The best part about separate CPanel accounts is that it separates domains more cleanly than using add on domains.

For example. if i have an addon domain called add and a domain called base,I would be able to access add using add.base.com or base.com/add

Adding a subdomain to that addon can be quite tricky