Welcome to FlyerTalk.

Here's a good primer on choosing FF programs.

Unfortunately, there is no one "best" program. What's best for you may not be best for someone else. Considering what you want to use your awards for can help narrow your choices. For example, if you only want to redeem for Hawaii, make sure you airline has plenty of flights there.

Also consider the recent codeshare agreements that Delta and US Airways have proposed.