Check this write up by Mike Kelly (Mike@MichaelDKelly.com) on choosing a test automation framework, with explanations on:
Test Script Modularity Framework,
Test Library Architecture Framework,
Keyword-Driven or Table-Driven Testing Framework,
Data-Driven Testing Framework,
Hybrid Test Automation Framework.
http://www-106.ibm.com/developerworks/rational/library/591.html#N10223