I guess it depends on what makes Boma your favorite.
We had reservations once and when we showed up, it just seemed to be chaos... lots of people moving around between tables, and LOTS of screaming kids. We cancelled and walked over to Jiko where we had a great, quiet meal. I like the peace after running around all day.
The food at Jiko can be a little exotic- but that's what I like. We specifically try different things that we wouldn't find elsewhere. Overall, the Chef seems to be excellent.
I also like that their wines are different- they usually let you taste a few of their recomendations. Some are terrible, some are great.. it's fun trying.