Polleni are supposedly oscar-like in their behavior, are from africa, and are stunning. They're not herbivorous though - but that means you could have plants with them.
Otherwise I vote for the Orbicularis or Synspilum.
Agreed that if you want that many polys, (esp. if you don't want to cut down from 3 Teugs to 1 or 2), you should just get a larger interactive cichlid and call it a day. When a fish is in your face all the time it makes up for the lack of movement in the tank. Most often the tank movement makers are just that and don't interact as much, so again - are they worth the bioload and work?
It'd be easy to add a small group of something after you upgrade if you still want it later on.
Boulengerella Maculata or Toxotes Blythii would be cool - you could get small groups and they'd give you surface action. (I'm just feeding you a list of fish that I want. LOL)
