We basically love all meals at all the restaurants at AKL (we will only be skipping Jiko on our upcoming trip and are trying Tiffin's instead). With nothing else being factored in, I would probably go with an 11:30 ADR at Sanaa (that is the earliest). The food is very good (the bread service is a must for us and I highly suggest it), we've always had great service there and getting in there first means you are more likely to get a seat at the windows.
With that being said, since you said it is the last meal of the trip, I am going to assume you will be doing some traveling shortly after. Not everyone's tummies can handle the African/Indian fusion and spices. I don't know your party and how you all typically handle spiced foods. If you think there could be an issue, play it safe and do Boma for breakfast.
Prepare for a great meal either way. Enjoy!