Kevin Wilkie lays out an argument:
If you truly need the UNICODE characters in your data, go ahead and use them! If not though, please make your DBA happy by not using them. Since UNICODE characters take up twice the amount of space as the ASCII versions do, then your DBAs will recommend to use the ASCII versions if you are not going to be using any UNICODE characters.
Read on for the justification. But I’m still NVARCHAR (Almost) Everywhere.