Based on your flying pattern, I think Delta is a very good choice for you. You will hit high elite status a lot quicker (double credit if you pay for business; 1.5 if you fly on an upgradable coach fare), and since the bulk of your miles are earned on international flights, you should have enough free upgrades to cover your domestic flying.

(The changes Delta made makes it more expensive to upgrade domestically, if that is the bulk of your travel).