I would do a sohal tang no aggression if you dont add another tang or a trigger.
They are also a false power blue tang (they are more of a purple color than blue) but am not aware if they are ich magnets as the pbt.
Mimic tangs are always nice and stay rather small, purples, yellow eye, flamefin, cheveron tangs add a lot of color. Nasos are nice, if you want diffrent body shape sailfins fit the bill.
Flames add a nice bright red color, but since you wont be adding coral you can add a butterflyfish the hardier ones always have nice colors.
Have you given a foxface a thought? nice coloring ESP. if you get a Doliatus Rabbitfish or Magnificent Foxface both VERY NICE!!
a school of blue/green OR blue-reef chromis would be nice to see school. Anthias makes for a nice small colorfull fish but some species are really hard to maintain. Lost of stuff to play with tom.