Local temporary table vs table variable - SQL Server 2008 R2/2012

Ok, therefore in a stored procedure that using a SELECT with more JOINs to get some millions of data I could use a temp table to insert the resulting set. Then I could have this temp table to compute a GROUP BY before to perform the final insert into a SQL table.

Or, in this scenario is it better to use a SQL table to produce the intermediate result instead of a temp table?

Thanks