Greetings!!

My family and I are moving to South Korea to teach and we're wondering what card we should be pursuing. Just a few facts about us:
1. We have Air Miles right now, but the return is terrible.
2. We will be travelling back to Canada once a year.
3. We have no loyalty to any one airline, and tend to shop for the cheapest price.
4. We will be travelling out of Korea whenever we get the chance.
5. Presently I make over $80 000
6. We don't mind paying a fee for a card if we have to.
7. Flying out of Buffalo or Toronto (Toronto is closer, but Buffalo generally much cheaper)
8. We spend $3-4000/month on credit cards (though this will not be used much in Korea because of Canadian Foreign Exchange Rates when we use these cards outside of Canada)

I have narrowed down to a few possibilities (though am open to suggestions):
1. TD First Class Visa Infinite Card.
2. Capital OneŽ Aspire Travel™ World MasterCardŽ
3. BMO World Elite MasterCard

I would like to get the card in the next couple weeks as we fly in July and I want to start booking and building points ASAP

Thanks!!