Both
I know it's taboo, but I have a Sohal (8") and a Clown (4") tang in my 230g tank. I've had the clown tang for almost a year now and it's very healthy. I added the Sohal two months ago and there hasn't been any agression between the two of them. In fact I had read so much about the Sohal and Clown tangs being so agressive I was waiting for disaster to happen, but I guess I got abnormal tangs because both of them are very peacful in my tank.