If you're going to be BKK based, it's very hard to go beyond TG. Airlines take best care of their own frequent flyers, and given TG offers most flights from BKK, you're going to be better looked after if you get some serious status with TG than if you bank you miles to another program.
One point to remember: SQ! If you fly SQ and decide to make TG*ROP your thing, don't forget the double dip to get TG miles and PPS credit.
I believe the OP said he's moving to BKK, not HKG.
I believe the OP said he's moving to BKK, not SIN.
I believe the OP said he's moving to BKK, not SYD.
Huh? The OP also said he's an Australian who will be flying all over the place. Regardless of being based in Bangkok, there's a legitimate case to be made that TG will not satisfy all his flying needs. In that light, I think BKKROP's responses are completely appropriate and address OP's potential needs. Seems that you're the one that's missing the Bigger Picture here. The point is to advise what might work best for ALL OP's needs (which may be multiple FFP's), not to be a defacto salesperson just for TG, though TG might be one weapon in his FFP arsenal.