What are you looking to do? New Zealand has two islands which, combined, are larger than the UK. We only have a population of 4 million though so whilst the cities are populated there are large tracts of empty country.
NZ great for :
1. Watching and playing sports,
2. Walking, hiking, camping, tramping
3. Warm but not roasting weather. If you want real heat, go to Australia.
4. Very friendly people
5. Generally positive outlook (much more so than the UK)
6. Breathtaking scenery
7. Far superior food, particularly in cafés
8. High performance Japanese cars are very common
NZ not so good for :
1. Big city life/'feel' (there's no London equivalent for example). Whilst Auckland in particular is quite bustly, it's not even on the same page as London for scale.
2. The driving here is shocking. If you're renting a car, be very aware of this.
3. You'll need to do a lot of travelling to see everything both islands have to offer. 4 weeks is acceptable but longer is better.
4. 12,000 miles is a long journey
5. Your pound is worth next to nothing right now. The lowest its been in a considerable while.
6. I can't actually think of any other negatives
Just so you understand, I'm not a kiwi banging on about how great NZ is. I'm a Brit who moved here last August and I'd previously lived in London for 10 years so I'm able to do some kind of comparison.
I don't know anything about South Africa other than they're a terrible pack of Saffer douches
