Hello! Do you have any ST Elite plus card? As a KL Platinum I would always choose to fly (Y) on AF/KL on DL stock, mostly because in a hope for cheap upgrade at check in. A380 upstairs isn't bad, main deck definitely sucks. DL can upgrade you to seat in main cabin with better legroom (I did quite a few flights between NA and SA vv)d. The food I'd say is identical. A330 will be boarded faster so more time in lounge and less time on arrival. If no status I would go for Delta.