Formatting dates in the presentation layer is best, because how the application wants dates formatted and how reporting wants dates formatted will be different, even if you get them to initially agree on a standard.

Still, formatting dates within the SELECT statement is tolerable and sometimes necessary.

However, containing date/time values in VARCHAR columns is perhaps one of the worst database anti-patterns ever. Not only does it require more effort to insure that all applications INSERT using a consistent format, but VARCHAR "dates" consume more storage space, and depending on the format, it often requires the use non-indexable conversion expressions in the WHERE clause.