I don't know what is available in New Zealand but I think "dual use" motorcycles are the best for beginners. These are basically dirt bikes that were made street legal by adding the required lights. These have an upright stance and are light and easy to maneuver. Yamaha, Kawasaki, and Suzuki sell dual use bikes in 200 and 250cc though some models are being discontinued.
The one drawback to dual use motorcycles is they tend to be higher than most bikes. If you are short this could be a problem. Sometimes there are more street oriented versions of dual purpose bikes that sit a little lower and sometimes your dealer can make adjustments to make the bike a little lower. If you are short this may not be enough. Should this still be a problem my next choice would be a "naked" or "standard" motorcycle. These are road bikes that lack fairings which can save beginners money since if you lay it down there is less to damage; these also tend to be the least expensive type of motorcycle. The only model I know of <=250cc is the Suzuki TU250X. If you need an even lower seat cruiser style bikes might fit like the Honda Rebel or Yamaha V Star 250 or Suzuki GZ250. If you don' t have your heart set on a motorcycle consider a scooters. For a lot of people scooters are a fun, practical, and inexpensive choice and there is a wide selection <=250cc.
From my friends experienced Honda makes crappy bikes. Of the 8 bikes my friend has owned or ridden, non of the Honda's still run.
He has a '76 Suzuki Endro 250 that is a great little bike for cursing around his place, and hitting some trails.
He had a Yamaha he loved but no one told him about some tensioning screw he had to tighten every ~1000 miles or so, or everything went to hell on that bike :P.
I did a ride on a Suzuki 250. Not too tall, nor too heavy IF it falls over ;) Sit comfortably on it, won't "run away". Good luck!!
Go with Yamaha or Honda- lots of dealers and good value.
Thanks, great answer. :)