I've kept hundreds of species. And, after 46 years in the hobby, I have to give the title to oscars. IMO, the most well-rounded fish for fishkeepers. They're not sedentary. They're easy to feed a wide variety of foods. They reach tankbuster size. They recognize their owners and get excited when anyone approaches their tank. They're found in a palette-full of color variations. They breed readily in captivity. Etc, etc, ad infinitum. Yep. Most well-rounded, enduring, endearing, and entertaining species.