It's a hard comparison...

Of the three I've visited (Cathay and JAL F now multiple times, AMEX once), I would rank Cathay the highest, love the design and views, the simple but good food, and the bar with an espresso machine. JAL F is nice for a whiskey, but the sushi was quite disappointing on my last visit. Didn't try any other food. The AMEX lounge has the best bar for drinks and is still a nice space, the food was also perfectly fine. However, with the expected overcrowding and small size it will probably not feel that relaxing in the future.
Without a question, all three are solid lounges and I would be happy to spend a short or extended layover in any of them.