135/2 = 67.5
85/1.2 = 70.3
200/2.8 = 71.4
The 85 only has a slight edge over the 135L for background blur if that background is well outside the DoF, but is no better than a 200 f/2.8. Blur circles sizes are proportional to the aperture size. At mfd the 135L actually has less DOF wide open than the 85L, since the magnification is much greater (similar mfd).
As to which lens I would choose. Well I would get 135L and Sigma 85 f/1.4 for similar price to just 85L II.