Ok thanks Rashkae for getting me to look up what bokeh actually means
"In photography, bokeh is the blur, or the aesthetic quality of the blur, in out-of-focus areas of an image. Bokeh has been defined as "the way the lens renders out-of-focus points of light"." - from wikipedia.
So its more like the quality of the background blur rather than the quantity of it.
Also shooting cosplayers at cosplay events is more like event photography rather than cosplay photography. Proper cosplay photography aims to recreate the feel of the original material which the characters are based from - the cosplayers will try to make an accurate costume, and learn the poses of their characters, the photographer will try to select an appropriate location and lighting (or set up his own) and shoot the cosplayer accordingly.
Virtually all the lenses from Rain5533's list can and have been used with good results (maybe not the 28 lol too new).