The optimum position for the space elevator would be equatorial. From a purely geometrical not practical point of view you could view the space elevator like the hands of a clock from a polar aligned position in space with a high enough altitude.

I wouldn't bother with a single collector for a number of reasons. I would use a mix of Lagrange points, geostionary and polar orbits with redundancy built in to a series of micro power relays and maser the energy to it. I'd look at using frequencies that would be easily absorbed by the atmosphere to minimize accidents and/or weaponisation.

This way the elevator becomes not only a transport mechanism but a way of increasing energy to earth.