AF had a dozen flight exHKG per week and a tough time filling them in premium cabins. It only has one daily flight exSIN and competes with SQ which offers a magnificent J product at high price. From HKG you can get Z fares valid either 1 month (with some fees for changes and cancellation) or 1 year without any fees. The 1-year Z fare is a bit more expensive but still a bit cheaper than the lowest CX fare.

Unfortunately, you dont get such deals exSIN because of loads on a single daily flight and expensive SQ. The current promotion in Z exSIN basically forces you into an inflexible ticket (no change, no refund). They might have the same promotion in 2010, but you must be very sure of your travel plans.

CX or AF? In my opinion, CX is far, far better than AF in biz (let alone for the flat bed), so if you can get SD$4500 on CX = WOW. But look at change/refund conditions. Of course, a nonstop AF SIN-CDG has a lot of advantages over the 1stop CX (HKG is 3h30 from SIN).