I think that that the massive quantities of Special Sweepers in the 5th Gen. allow for many new Choice Specs users. However, In older generations, most Special sweepers either
A) had such a giantic Special attack stat that there was no need for Choice Specs; instead, they utilized the Choice Scarf
B) They were too slow, so they used the Choice Scarf
There are also many amazing Choice Band sweepers. And the good thing is- They are usually very fast. Therefore, my pick is the Choice Band.