A green terror. Large, personable and hardy, but not a giant like an Oscar. Brings attention to itself. Feed it once a day and change water once a week (like any other fish) and it'll require nothing else. Going for the big fish idea since the smaller ones have been taken
You could always look around for one (or two) species of tetra or other schooling fish that you like, get a large school of those, and add a bunch of cories or maybe shrimp. Idk the specifics of your tank but that's what I would do. I have a soft spot for some color/ pattern coordination, so I'm thinking something like Rummynoses and Julii Cories, Cherry Barbs and Bronze Cories, Black Neons/ Emporer Tetras and Panda Cories, etc.
If you're looking for a bit more of an oddball, Blind Cave Tetras are awesome. They can get about 4 inches and look quite different than your standard fish, so I think they're a good attention grabber. If you did want something to pair them with, I'd again suggest something like Albino Cories, Amano Shrimp, or Ghost Shrimp to keep up with the pale, ghostly vibe of the BCTs.