I have only been lucky enough to eat at Flying Fish and Jiko. Both of these meals were fantastic.
For a single diner, I would choose Jiko. Our waiter was wonderful. Explained alot and spent time just talking (we had a late reservation, so were his last table - I think). At Jiko, you can sit over by the open kitchen, so if you didn't have a tablemate to talk to, there would still be something to keep you interested.
Food was wonderful. I do not eat seafood so I had the Ostrich (very tasty and I would definately try again - it has a beef taste), then the filet with the mac and cheese (the filet was melt in your mouth incredible. I have heard many great reviews on the mac and cheese but, I thought the wine taste was very strong and therefore I didn't enjoy it) and finally the dessert was chocolate cheesecake with lavender ice cream. Never thought of this flavor of ice cream as something I would try but it was very light and refreshing and paired wonderfully with the heavy chocolate taste.
Best of luck in making your decision!