I have always liked the Jack Dempsey the best. I also think they are very over rated as a aggressive fish. They can be very territorial as any cichlid is apt to be, but I have raised many from young juvies with tank mates that have raised many a brow, but it has been my experience that when all are introduced together at a young age and kept together all goes well. It is when you introduce a new fish at a later date that things can happen...
Watching cichlids during their mating rituals is truely awsome, then watching the care they take in making their nest and then the raising of the fry is really interesting.
Convicts are excellent choices if you have never breeded cichlids and want to try. in my opinion they are the rabbit's of the cichlid world.
BASS