It costs far less in delta-v to lauinch from a site closer to the equator for an equatorial orbit (ie LEO, GSO). Point: Canaveral, being at 28N. NZ is at 42S.
There's a bit of a physics cheat being closer to the equator and launching prograde to rotation. At the equator, this amounts to 1,000mph, the advantage diminishing as you go toward either pole. Winner: Canaveral.
This advantage negates any advantage launching from closer to the pole for a polar orbit. Winner: Canaveral.
someone want to tell me how launching from NZ, apart from political issues, is in any way advantageous over launching from the US?
(BTW, to keep it in perspective, Baikonur Cosmodrome is at 45N. It suffers from the same DV overhead over Canaveral that a NZ site would, which is one reason the Russian launchers are bloody humungous).