Originally Posted by
watermen
I fly frequently within the country (USA).
To where? How frequently is "frequently"?
Originally Posted by
watermen
Using points to buy tickets isn't really my goal, rather I hope to achieve a million miles and get lifetime Elite status, so I can get upgraded easily with a cheaper ticket.
3. I fly to Singapore a few times per year. 2-3 times.
You're not getting upgraded to Singapore very often just based on MM status (which, at 50,000 miles a year, would take you
20 years of flying). Longhaul flights like that are the ones that airlines an get the most money for, and consequently are the least likely to be given away. It is
far more realistic in your situation to accumulate miles and then occasionally get a NYC-SIN flight in business or first class than to expect complimentary upgrades.
The complimentary upgrades would be more likely on shorter domestic flights. Sure, that's nice, but in a metro area like NYC, you're fighting with a lot of people: flying even 50,000 miles a year isn't very impressive (won't get you a lot of upgrades on the airlines based in NYC).
Honestly? Either Delta/DL (with some occasional Korean Air(KE) redemptions or American/AA (with occasional Cathay Pacific (CX) redemptions) could work for you. I suspect that you would find better luck redeeming on CX (KE has lots of award blackout dates).