I have to respectfully disagree with the OP. If you buy an econ ticket on SQ and CX and CX upgrades you of course CX provides better food and service! But comparing apples to apples, SQ is definitely better than CX in terms of food and service.

I have flow CX F for many years and in the past 2 years CX J. Now flying SQ I see a big difference in food (especially in J) and service SQ wins hands down! SQ anticipates what you need, you don't have to ask. CX can sometimes be very good but sometimes very bad. CX F I've had 95% excellent service but only 50% good service in CX J. On SQ J, I haven't had a bad flight yet!