I've only been to Boma once and only for breakfast, but despite all the glowing reviews, I was super not impressed. I was expecting a wide variety of African food with a few "classic" buffet foods. Instead, I think that there were maybe 2 rice dishes that were "African-inspired" and then just a bunch of typical Golden Corral-type food.
Also, it's loud and the line to the buffet was long the entire time we were there.
It was easily the worst ADR of our trip last week.
I haven't tried Jiko, but probably will next time.