Technical Support
Address Autocompletion (TypeAhead)
Ease of Integration
E-mail Validation
Support for many countries (other than just Australia)
AMAS Certified (Australia Post)
Price
Performance
Platform support (i.e. different ways of getting the software)
Australian-made/Australian-owned
Phone Validation
Full address validation, right down to the premise level
Ease of use
Maturity/Stability of the company
API