If you have MR, TYP, UR, or SPG earning credit cards:
1. Calculate how many Elevate points you would earn from the flight.
2. Subtract that number from the total mileage for the flight (gcmap.com)
3. If the result is positive, credit to SQ KrisFlyer, assuming your fare class is listed on this chart:
https://www.singaporeair.com/pdf/pps...FOALLevels.pdf
4. If the result is negative, credit to Elevate.
If you don't have any of those cards, you're probably better off crediting to Elevate.
Don't credit VX economy to Flying Club. You'll only earn 50% of flown miles.