I'd say its personal preference. I like mine down although on the sides of the mirror is the ideal. Wish I'd known that before we built our house! Down light seems more practical for me since I want the light for hair and makeup vice for the rest of the room.
Whatever you choose, its easy to change later! Just turn 'em around :)

my husband likes them to point down - then dead bugs fall out. I like them to point up - don't like seeing the light bulbs. I've seen many that you can only mount one direction, and have several that can be mounted either way.

If there is a "right or wrong" direction, that is something new to me. Always thought it was based on the fixture and personal preference.

Thanks so much for accommodating me! We (I!) decided to face them down. I called the company, and they can be turned either way; so I will have that option. You guys are great!