They are all territorial in their own right, but maroon's and tomato's seem to be the worst and get the largest (of those available), which doesn't help. I do love maroon clowns, though
You could try a Cirrhitichthys oxycephalus, Pixie hawkfish or a Cirrhitichthys falco, Falco hawkfish. These do not get large, but may try and consume shrimp. Cardinal fish are another option.