Niger,Pinktail,Sargassum, and a Picasso(with reservations according to individual fish tempermant) will work. THe Picasso CANNOT be housed with another trigger unless added together(as I found out the hard way, a Niger I had did battle with a Picasso that I tried to add to the tank, needless to say the Picasso was pulled out within 30 seconds.)
Of them all I find the Pinktail to be the best mannered and the most timid. Gets along great with smaller fish like firefish,chromis, mandarin etc. Pinktails I think are a very special Trigger fish. They have ALL the personality without the nasty temper. THey are also real pretty too in my book. Really nice scales,shape and color. A great fish that you cant go wrong with.