"I prefer the extra compression"
I'd challenge anybody in a double blind test to accurately be able to tell the focal length used between the two lenses. Focused at "normal" portrait distances it wouldn't surprise me if the focal lengths were almost the same anyway.
35% more compression and the extra stop of speed is what made me make the same choice for the 135L. Its also the reason I decided to pass on the 85L for portraits, too tight and it will produce bigger noses.
These are my tastes and If I was able to notice the difference, that's enough for me to choose 135L > 100L for portraits.