Hi Whale and welcome.
To get a foot in the door, I think perhaps concentrating on getting a good job would be the priority rather than pondering on which would be the best place to live. It would be great to be able to pick and choose where you'd like to go, but that wouldn't be much use if the only job on offer is in a different area. If you get offered both jobs and neither one is better than the other, then you have the awkward decision of which one to choose. If only one is on offer or is suitable for you, that is probably the one you'll have to run with, whether it's in Auckland or Christchurch. I'd go along with the others who say you can always move around once you've been in NZ a while and have a better idea of the country. Getting the job in the bag is the most important thing initially, as that will form the basis of your life there. There have been several members on here who had their dream destination and went there only to find there weren't any jobs or the place wasn't so ideal in the end. They moved elsewhere and have been happy and content.
There always has been and always will be the old north/south divide with some swearing that North Island is the best place to be, but others are equally adamant that the South Island is wonderful. No doubt both are right because it's where
they are happiest. Everyone is different so the choice has to be yours alone.....if you are given the choice
.
The best of luck with your interviews. Hope you can manage to get some rest in between all the dashing about.