well it depends on what you want out of your tank really. I like both personally but for diffreent reasons. I like the africans because they are easy to breed, have great colors, easy to sell, and they like to move a lot. I like americans because they are personable, a little (not much) harder to breed, they (for the most part) are larger, and they are colorful in their own right.
Things i don't like about africans are, they seem to have only two things on their minds( breed and eat) very little puppy dog sensation for me, and they they are more expensive(for the most part) then americans. What i dislike about armericans is, the tank size needed is based on aggression more so then size, all the ones i like are hard to find(except online), and they require a delicate balance in a community setup.
How this helps.