Who buys a wide angle for bokeh? You're subject will have to be really close for any kind of blur but really? Come on! 17-40L or 24-105L is pretty obvious. 105mm f/4 will give the most amount of blur. As to the quality of the blur - it's alright, nothing special.
You'll get nice bokeh with - 50L, 85L, 135L or even the 85 1.8 which was designed with bokeh in mind. 50 1.8 will give you ugly pentagons when stopped down and 50 1.4 is kinda in the middle. The 70-200 lenses all produce nice round oof highlights too and at 200mm f/2.8 everything in the background melts away into oblivion. Bokelicious!