Next month I'm hoping to use miles or points to fly SIN - BKK - SIN in Business. I primarily earn miles and status via UA/*A so the easiest route is to use miles from my UA account to pay for the tickets but I'm interested in getting the best value for the transition that I can. I have enough points in each of these Programs as well: Citi ThankYou, Chase Ultimate Rewards and Amex Membership Rewards

So far I see the following rates when booking through each respective plan:
KrisFlyer: 40K Miles + SGD 80.50
MileagePlus: 50K Miles + USD 59.00
ANA: 55K Miles + JPY 11,610
Aeroplan: 80K Miles + CAD 77.50

I've never purchased an award ticket using Credit Card points directly, nor have I specifically booked a with a carrier from another alliance with miles/points.

What would you recommend as "best bang for the points" in C to fly SIN - BKK - SIN?

Thanks!