Each airline program is different (both earning and redeeming). For your stated purposes AA is by far the best. But every program has something that it is good at (for example, QF requires more miles than AA to redeem LAX-SYD travel on QF -- really! -- but it has much better award availability, particularly if you can book 355 days ahead ... so is a cheaper award that is rarely available worth more (or less) than a more expensive award that you can fly on?).