Up would be ideal, if it is bright enough. Down would cast shadows, but also be brighter. Have you considered a lighted makeup mirror and up facing fixture? As a rule depending solely on a 3 light bar to provide adequate task lighting doesn't always deliver. Consider pairing with recessed cans, ceiling flush mount fixture or lit makeup mirror for ideal results.

response to Robbie and Lisa. .this is the main bathroom mostly for kids but I do have friends stay over. pot lights not an option at this time. Two alike lights over the 2 sinks. This bathroom will also be our master bath temporary replacement during the next reno in the master bath.

Ohhhh in that case, 2 fixtures facing up with a small lighted makeup mirror that you can move with you when your master is done.

Down. Why the heck light the ceiling. The "shadow" is not much an issue. Many many lights can be mounted in either direction

Dead bugs gather in up lights.

Mine are down in all my baths. No problem re shadows.

I have no idea why you would want to light the ceiling.

I always have to wonder why people light up a ceiling when I see them hung upwards.

So, down and glad you asked, as many don't.

Very interesting comments....seems down has the majority. Thanks All!

yeah....... especially the bug thing : ) Point 'em DOWN lol bonus is you can see the toothpaste smears in the sinks.

down lighting as I just started following and it's my vote :)

Or instead of a fixture above the mirror, use sconces on either side of the mirror, facing down. Then you won't have shadows or bugs ;)

or sconces with shades: