I must be the only real fan of the Libyan/Heavy Libyan Spearmen. Far more vaersatile and deadlier IMO than the Liby-Phoenician line of spearmen. I generally mass-produce Libyans and anchor them with either Elite Afircan or Sacred Band pikemen. I prefer Numidian Skirmishers of both cavalry and infantry stripes and you can't go wrong with the Carthaginian Citizen Cavalry. Damn solid cav they is. If you can spare the cash, a Sacred Band Cav or two works wonders.
Of course, if you are in Iberia, use the locals. Solid infantry and cavalry, and the Iberi Lancaeri may just be the best heavy cav in the game (no offence, Hetairoi and eastern cats).
My exact makeup depends on what section of the world I'm in and how rich I am at the moment. The numbers I give below are just ranges and do add up to more than 20 (since it can vary over time)
In Africa proper:
1-2 General
8-10 Libyans
2-4 Heavy Libyans
2-4 Numidians (Cav or Inf)
2-3 Carthy Citizen Cav
1-2 Sacred Band Cav
1-2 Sacred Band Inf or Elite African Pikes
1-2 Elephants if you desire 1-turn sieging or cav killers
In Iberia:
1-2 General
8-10 Libyans or Scutarii
2-3 Iberi Velites
2-4 Iberian Assaults
2-4 Iberi Lancaeri
2-3 Gaesatae (if N Iberia/S Gaul)
In Sicily/S Italy:
1-2 General
3-4 Lucanian Light Inf
2-4 Carthy Citizen Cav
4-6 Elite African Pikes or Sacred Band Inf (Libyans or Heavy Libyan if no MIC high enough)
2-4 Liby-Phoenician/Heavy Liby-Phoenician (or local Hoplites)
2-4 Samnite Spears
2-4 Samnite Milites or Iberian Assaults