It’s a tricky call but the £800 price differential does make the decision a LOT easier.

In a former life I had cause to travel out to - and within - the African continent once every two months or so, and found KQ biz class to be perfectly satisfactory (albeit I was booking regional rather than long-haul sectors with them)

i suppose when comparing them with BA, you might have potential concerns about inflight service standards, mediocre food, poor boarding processes, CC chatting noisily in the galley - but worth remembering that any / all of those things can sometimes affect Kenya Airways too, and are certainly not unique to BA.

Enjoy …… whatever your choice.