I have kept so many types of sa/ca cichlids over my 7 years of fish keeping.
buy far, my favorite is the astronotus ocellatus ( Oscar )
Something about them... I just really like them. In the 7 years of me keeping fish I have had a oscar. There personalities are like a dog how they beg for your attention and beg for food. They are also very smart and can be trained to to simple tricks.
Right now, it's my silver arowana because he's a loner who is always on the prowl for food. He continuosly paces the length of the tank like an aristocrat. He has a certain non-violent arroagance as if he's the king. My other fish act like his subordinates.
I really like green terrors, but my GSP has so much personality, he looks like a fat little nerdy kid, but will kill just about anything I put in there. They way they move is cool too its like having a water helicopter.