I've got T. nigriventer, and they are in my top three favs. Also have some Champsochromis, which I also absolutely love. I'd go with those, personally. The Champs are largest and definately aggressive. I have a feeling, though, that if the Tyrants were larger....they'd be just as bad.
BTW, you've got a great problem (a huge empty tank and the sky's the limit on what to fill it with....if only I was having that problem right now