I must say that AF with the 1-2-1 configuration has a better product in general but the difference isn’t as big as it used to be.
Please be aware that AF still flies the 2-3-2 occasionally on this route which totally destroys the experience. KL guarantees an acceptable product. AF doesn’t.
The catering in general is better at AF, I have had really amazing dinners in AF long haul in J. But recently from CDG to LAX, the catering was terrible. I chose the chicken which was dry as sand and also the pre arrival meal was forgettable while LAX-AMS onboard the B78X was fantastic, has an amazing mexican dish.
the crew at KL is much friendlier and hospitable but then again, AMS is easier transferring but the AF lounges are just superior.
When everything is said and done I would chose AF.