Alitalia is a SkyTeam member, but their FF program seems to me to be run inefficiently and has some funny features: apparently it mmust dissolve about every five years, with all remaining miles being wiped out at that time, regardless of continued activity or how recently the miles were earned.

If you're going to be flying AF/KLM into Africa, then the obvious FF program choices are either FlyingBlue (AF/KLM) or Delta.