They're both recognised courses, so they would both be good enough to get jobs in many countries. If I were looking at your CV and saw a course that had a lot of classroom practice, I would be more attracted than to one with a minimal amount, which inclines me towards the second.
As an old fart, the fun element doesn't grab me greatly, and remember they are the ones who say it's fun. I've been through so many training courses that when people talk about fun, my hackles go up. Also, the purpose of training isn't to have fun, and how much fun will you have reading a manual alone at home? The job guarantee is good, though there are plenty of jobs out there- have a look at some of the job boards.
You can get most of the culture shock stuff from a copy of the Lonely Traveller or similar. Anyway, it's just learning a few no-nos and being able to adapt to different lifestyles, which from my experience is something people either have the ability to do or not. It's not that difficult anyway, and I have lived in various countries. Besides which, the internet is swarming with forums full of teachers from all over the world who can help out there.
I can't help but incline towards the NZ course as the certificate would impress me more if you sent it to me. However, I would still recomend looking into the CELTA simply because it so widely recognised- look at how many adverts use it as the standard qualificatioon of measure for a qualification, though the polytech course smacks of being very similar.
- For Teachers