J, Ecuador sounds reasonable, although in my opinion nations around it may not rest in peace in case of such a war. Moreover, the possible resources of oil in the area may be targeted by powers in need of energy.

As for northern Canada, Greenland or any Northern Hemishpere nation, I'd second what Silverboy has mentioned in his post on this topic. The effects off all the firepower, radiation etc may become hard to live with anywhere there. Russia, for example, with one bomb, which it apparently has in its arsenal, would wipe out the whole NY state in seconds. Such a firepower must be strong enough to be damaging for either the Northwest Territories or Greenland.

On the other hand, NZ that is far down in Southern Hemishpere on its own may more likely be untouched by the consequencies of all the nuclear war in the Northern Hemishpere. This nation has some fine mountains and farming to offer which both could come handy during such a global tragedy in which food may disappear quickly. Perhaps, Silverboy, who I have read somewhere is from NZ, may enlighten the forum with the kiwi (and sheep) choice.