To me, CTE's have the advantage of Derived Tables because you can reference them many times in the same query at different levels in the query whereas a Derived table can only be referenced one level up in the same query. It's not a huge advantage until you actually need it. CTE's also (to me, anyway) present themselves nicer for readability and documentation purposes. They can also call themselves (recursion) like a function might.

Temporary tables have the advantage over both because they persist for longer than just one query. I used (and still use) temp tables in place of CTEs ("sub-query refactoring" in Oracle) long before they were available in MSSQL. In fact, if I know a result set must be used across many queries in a sproc, I'll still use TempTables instead of CTE's. I like "local" temp tables a lot... I wish Oracle understood the concept as well. Their "global" temp tables don't work out quite so well.