We tried both on our last trip in September. Here's my take:
Coral has better atmosphere. It is unique, but then, how much can you watch fish tank while eating? Maybe it is also a little disturbing to watch fish while eating fish. Didn't really bother us.
Both had very good service overall.
Chefs had shorter wait for table. It seems like there is always a wait at Coral to get your table, evenwih an early ADR time. Chef's wan't an especially quick meal though. French service is notoriously slow paced (part ofthe culture), enjoy a break. Our server really went out of his way to be nice, but it wasn't our quickest meal.
The Kids' meals were far more generous at Chefs, but look over the options at both (ahead of time) if you have kids to make sure they will like the options. One choice at Chefs is a hamburger- description is more flowery so it's a little unclear; it's a good burger. Many TS places now have fairly limited options for kids.
At Coral, Mahi mahi was excellent. We ordered it with plain rice, my meal not as good. At Chefs, steak filet was not great. it tasted oddly burnt. (may have been the sauce?), but it came with excellent green beans. (Green veggies can be hard to come by at WDW. Worth getting a side of gb, even if you pay oop for them.) My food, a shrimp/scallop dish was tasty, if not a huge portion. Someone next to us has somthing that looked really great....I'm not positive now, but looking at the menu online, I think maybe it was the salmon on salad greens.
