I would go with a 6ft 125 if that's the case and avoid a corner tank if you can it will give you more options.
agreed
if you wanted a green terror and jack dempsey a 100 gal would def be sufficient and shouldnt have too much of an aggression problem with that much room, i have a green terror and jack dempsey in a 55 gallon and they get along great, all depends on each individual fish's personality though