Occam's razor pertains to competing hypotheses that attempt to explain some phenomenon, not the question of which of several equivalent formulations is best.
If you argue that there can only be one, I say tau is better. But to me it's less confusing to have both tau and pi, simply because both of these graphics seem very fundamental to me:
Well, today I think of Occam's Razor in the spirit in which it was originally offered, according to one translation, "One should not needlessly multiply entities."
Not only is it a great answer to the original question ("How many angels can dance on the head of a pin") but it is a great engineering principle as well.
So I agree with the GP who says that use of two competing variables which differ only by a factor of two is redundant and runs up against this principle.
If you argue that there can only be one, I say tau is better. But to me it's less confusing to have both tau and pi, simply because both of these graphics seem very fundamental to me:
http://tauday.com/images/figures/tau-angles.png http://www.thepimanifesto.com/areas.png