Sells better?
Thats going to depend on several different factors. Are you talking of trying to breed?
Both fish are part of the Aequidens/Andinoacara family of South Americans. BUT both have a much different behavior and attitude. As far as Green terror are you talking about andinoacara rivulatus? Or andinoacara stalsbergi? WHile they are both Green terror they are different and one is much more less common. Blue Acara's are a much better community fish with a mellower attitude while GT's can be sometimes but can also be more aggressive at least when dealing with Rivulatus "Saum" Green terror. Im willing to be more people have and buy Green terror, but I could be wrong.
You forgot to mention that there is 2 commonly available types of Blue Acara also, Andinacara Pulcher, Andinoacara Latifrons, there is others to but not as common.