Jiko is my favorite restaurant in Disney World, so it's weird for me to advise against it. But if you can't do both, I think you should try Sanaa. It's very good and worth trying.
Actually, if you can swing it, I'd have an appetizer in the lounge at each. Both have good entrées but even better appetizers. You could do something like have a drink and bread service at the Sanaa lounge and then go have an appetizer and dessert at the Jiko lounge.