SQ and CX are on par with one another in all cabins, both are excellent airlines. Since the question was asked on an AA Forum, I'm going to bet the OP is interested in maxamizing their mileage earning to the AAdvantage program for the long trip, and CX (via SFO or LAX) would be the best way to go. There is no question that AA F or J leaves a lot to be desired when compared to the International Flag carriers.
Although, if he flies on AA metal most of the way, he could use his VIPs to upgrade to F. AA F should compare pretty well to J on other airlines (although probably not to F on the other airlines, but it doesn't sound like that's an option).