It depends on who is in your party and what their taste buds are like. Boma is a buffet, so you can try a lot of items. Most are pretty standard, but there are a few with an African twist. Also, being a buffet, means a pretty casual atmosphere. Jiko is a table service restaurant (it happens to be a Signature), which means everyone orders off the menu. So you're more limited in that way. That being said, the food at Jiko is excellent. Lots of very good items, many with an African twist. Also, being a Signature, means it's much quieter and much more subdued than Boma.