Best Method to Import to SQL Server

What is the best method to import into SQL Server?  I want to bring a flat file into a database.  As part of the process I want to apply some basic rules of insert/update/delete.  Is the best method to process the file in BizTalk record by record and send it to various ports based on a promoted value?  Is it better to send to a stored procedure and let it do all the work?  Is it better to use an updategram?

 I know that better is a term that is arbitrary.  But I am looking for a general answer of speed performance and flexibility.  If you needed to bring in some flat files into a database and apply some basic business logic (at some point) how would you recommend doing this.  I am asking as I am a DTS/SSIS person and would normally just do it in that and use stored procedures.  But we are trying to make it a little more dynamic in that we can change receive port and then hopefully with minimal changes get it into the database.

 Any disucssion on this, requests for further information would be welcomed.

 Thanks…