Sanaa is a very specific cuisine, and reviews are constantly favorable IF you enjoy Indian/African spices and textures. I love Boma, and I actually did dinner 2x last year: lots of variety, some unique items, and some very familiar items! I really think you are choosing between two winners, and just have to figure the style of dinner you want...plated and quiet, with animal views (if during daylight,) and specific menu, or more active, buffet, with soups, salads, carved meat, mains, dessert assortment.
BTW, there are animal viewing areas at both hotels, so that should not be a deal breaker...wander outside at your leisure.