I guess it depends on your taste. They are very different restaurants. I have eaten at both.
Boma is a buffet. It has a variety of different foods and some are very different. It is pretty inside. We have eaten there 4 times and have never had a bad experience. It is at a resort so travel might make a difference in your decision.
Raglan road is very home feeling inside. The service was amazing, but we were very disappointe with the food. it was very plain to us. It is in DTD so it is convenient.