I recently got a Dark Prophecy battle staff with 32" blades. My review is
here. The total length for this one is 6' 4". I am 6' tall and it seems just right in size. I have a few friends that have tried it out who are shorter then I am, down to about 5' 4",, and they also think it is about the right size.
So unless you are really tall or really short the 32" blades are probably the best bet. Except for maybe something crazy like a War Glaive battle staff.