Eaten multiple times at both. Leaving logistics aside, Sanaa wins hands down for me. Have to admit, I am influenced by the relative availability of Chinese food and the lack of Indian food in my hometown. I greatly enjoy Y&Y, especially the wonton dessert! But EVERYTHING at Sanaa is great. Bread service is awesome, marinated salads are great, haven't had an entree that wasn't enjoyed. I particularly love the paneer tikka!
If I was at AK and needed a relaxing meal in the middle of the day, I'd do Y&Y. If it was at the end of the day - Sanaa without question!