I would take physiology, and my reasoning is this:
You WILL see plenty of each of these subjects again, although the anatomy (depending on the dental school) may be quite a bit more limited.
For me anatomy has always been a learn it and then forget 90% of a month later type of course. Physiology, on the other hand, I've remembered, especially the basics of physiology which is just good stuff to know.
I'd say you ought to at least fit physiology in, as it will give you somewhat of a foundation prior to matriculating. You really ought to have some phys. foundation prior to entering dental school.
That's my two cents.