I've flown with KQ numerous times, both from Europe and across Africa and I would have no hesitation doing so again. It's not just that they are far more generous with frequent flyer miles than BA, but I genuinely prefer them as an airline. If you are in the back of the plane, the choice of films on the IFE leaves something to be desired, but that is the biggest complaint I can come up with. Handling by KLM at T4 is probably better than BA's equivalent, but there is no real difference in how things are handled on leaving NBO.
In terms of safety, as far as I'm aware, KQ have a very good record which stands comparison with most major airlines.