I'm living in South island now and the scenery is amazing. I haven't been to north island yet though so I can't really say which is better.
If you do choose south island, though, I must say that Milford Sound and Mt Cook is a must-visit. :)
Beautiful collection of photos! I really like your composition and framing :)
Oh and photo no.7 kinda reminded me of that photo by Gursky that sold for $4.3 million ;D