Does KE allow flights in Delta to qualify for MM program? Some FF programs require flights in their metal before they bestow upon you the lifetime status, so make sure you are allowed before you move everything over.

AA used to have the best program but now it's changing. You still have a chance to get 3 AA cards and hit spending before Dec 1 to get a head start of 225k miles. If you spend a lot their MC is suppose to give you miles for another year with a hefty fee but might be worth it to get you closer to lifetime gold (1 million miles).

At least with AA you can fly other OW partner and have that count towards LT status.