I believe sooner than later we could see end of bull market for both AUD and NZD once we see shift in the currency cycle. We could see bigger drop in NZD and AUD against USD especially during second half this year. Thereafter down trend could continue until 2016 while having volatility. In short both NZD and AUD are more vulnerable now.
My ideas are not a recommendation to either buy or sell any security or currency. Please do your own research prior to making any investment decisions.