I have an Oscar that's about 10 years old. Honestly I don't know how he's lived that long because I hardly have time to take care of his tank since I had kids. Plus it's a smallish (55 gal) tank, so he's not that big - probably a foot or so. I've also had African cichlids. I've never been able to keep them alive too long because they're less hardy than Oscars, so I don't know if they get as big, but they are far more aggressive than the North/South American cichlids.
Jack Dempsey's are prettier than Oscars, and I had one that lived several years but died in a tragic moving accident. They seem more aggressive than Oscars. The links you provided don't do them justice - they have nice blue and red colors that go nicely with their spots.