User: Who is the best men's test cricket player to have come from New Zealand?
Assistant: Despite a rich cricket tradition in New Zealand, the country only became a test playing nation during the season of 1929/30, when the MCC toured the country playing 4 tests. Australia, the nearest test playing country to New Zealand, refused to grant Test status to any games played between the two nations until well after World War 2. This lack of test opportunities led to a now common path of talented New Zealanders moving off shore for the chance to play test cricket- most notably in the pre WWII period of Clarrie Grimmet, who took over 200 test wickets playing for Australia. Since then, Andrew Caddick (234 test wickets at an average of 29.91) and Ben Stokes (5000+ test runs and 196 test wickets) have played leading roles for England in tests.

If however we define the question as "the best test cricket player to have played for New Zealand", then there are perhaps only 3 or 4 candidates that feature. Of the current generation, there is no doubt that Kane Williamson will one day be regarded as the greatest player to have come from New Zealand- with over 8000 test runs at an average north of 50. With many years in front of him, Williamson will no doubt hold the crown of best test cricketer in years to come. 

Martin Crowe must likewise be regarded in the pantheon of test greats to have played for New Zealand- despite a slow start to his career, and injuries curtailing his time in the team, he amassed over 5000 runs at an average of over 45.

However, most will agree that the most influential cricketer ever to play test cricket for New Zealand was Sir Richard Hadlee- the first cricketer to be knighted whilst still playing cricket for his country. Hadlee's bowling average of 22.29 is one of best in test cricket history, and at the time of his retirement he held the record for test wickets, at 431. Gaining 5 wickets in an innings 36 times was also a record, and led New Zealand to some of it's most famous test victories, notably victory in a series in Australia for the first time in 1985/86, with his best test figures of 15 for 123 coming in the first test at the Gabba. Added to his bowling, his destructive lower order batting made his one of the preeminent all rounders of the game., and truly NZ's best test cricketer.