For traffic movements FAJS and Cairo are definetely up their. I think FAJS pips Cairo though. Interesting point is that the FAJS - FACT route was the 11th busiest city to city pairing in the world a number of years back. Rumour has it that it is now in the top ten. This is unsubstantiated and would be interesting if any one knew more. The top 5 in SA about 3/4 years back was:
1. FAJS
2. FALA
3. FACT
4. FADN
5. FAWB
As far as general aviation goes, FALA is the busiest with Wilson being 2nd. Both still fall short of FAJS/Cairo.
I agree with Lagos having the most potential. It is ideally situated has a hub. Pity it has nothing else to offer. One only has to look at what Emirates Airlines and Dubai are doing to see what can be done.
Generally airport business is rated according to pax and/or cargo.