I keep BOTH American and African cichlids. BY far i like African cichlids better.
I;ve had Trimacs, festaes, carpintis, etc... All great fish, still have em. But I like the exotic look of Africans. WHen people come over, I get a lot more complements on my African tank.
Haps/Peacocks also tend to be more expensive than most Americans; so not the fish for the inexperienced. BTW, ppl think of Mbunas (common Petco africans) when they think Africans. Mbunas are like 20% of all Africans cichlids. You can also overcrowd tanks to curb aggression; very common practice.
Here's a couple good vids of a Hap/Peacock tank:
http://www.youtube.com/watch?v=H9m2EDlsg2M
http://www.youtube.com/watch?v=70kXDwZk8mw&feature=related
http://www.youtube.com/watch?v=Rr3UMII0VU8&feature=related