In reply to Phil Layton:
Yet another vote for UK... I have lived in NZ, I absolutely love the country, but the rock climbing is pretty limited. A good chunk of the rock there is choss, even in some of the 'popular' (in NZ terms), newly developed crags are still dropping bits all over the place. The Darrens is meant to be amazing for alpine granite, but it rains a LOT (hence why I never made it...) and is far from a cragging day. Castle Hill I'm sure is amazing (I'm not a boulderer), it is an incredible place to visit even if you're not a climber. Payne's Ford is ok. Alpine rock is generally very chossy.
The UK has quality rock within relatively short drives from wherever (distances in NZ are deceptive!), a huge variety, much more trad (if that's what you're into), more of a scene.
However, NZ is, as others have said, fantastic for getting away from the crowds, the mountaineering is amazing, and it a very beautiful country with some very friendly people.