Westpac and ANZ are the only New Zealand banks to gain a five-star rating for their owner-occupied mortgages from financial product research company Cannex.Cannex rates mortgages on both the cost of the loan and the features offered and say this provides the best method for consumers to judge true value-for-money.ANZ rates better on costs; but Westpac's superior product features give it the best overall rating.For residential investment loans, Cannex gives greater weighting to costs and this helped ANZ to take the number one spot from Westpac in this category.National Bank of New Zealand has the leading line-of-credit (home equity) product with Bank of New Zealand and Westpac also rating five starsInterestingly, ANZ's owner-occupied and investment products rate better than NBNZ's, but the latter's line-of-credit products are superior to ANZ's. No doubt, this will lead to some spirited debate as the merged ANZ National Bank rationalises its dual-branded product range and attempts to arrest recent declines in market share.