When i was living in Chch as a young fella and going to the races Reon was the caller i heard and was always a fan so i'd rate him on top for mine.Not far behind would be Mark Mc,who hopefully is staying after reading all the comments here.And then in no particular order i'd have Tony Lee,Matt Cross,Keith Haub,George Simon.Heard a little bit of Allan Bright before he retired and he didn't do a bad job and i never had the pleasure hearing Peter Kelly or David Clarkson but sounds like they were damn good.
I noticed someone mentioned Greg Miles in Aussie...yea he and Matt Hill would have too be my faves over there.Also Darren McAullay(i think) who calls in Perth seems quite good.