Bjoernyy wrote in post #16905803
Yes, why not the 100mm 2.0? Isn't it better in combination with the 50 1.8? The 135 2.0 is much expensive, is it fair for the price? Because the 100 2.0 costs a party of the 135mm 2.0...
How is the bokeh difference?
I am basing my lens recommendation on the choices you provided.
While a 85mm lens would not compliment you 50mm lens as well as the 100mm or 135mm in terms of FL,
it may not be a reason not to get it.
The first step is to determine what kind of portrait you want to take and how much room you have to work with.
(physical room to back up, etc)
The 85 1.8 give you the widest view of the three lenses and therefore be the most useable option.
The CA is know to be 'bad' on the lens wide open, but easily corrected in post processing.
If I had a 135L and I could not back up more, all I would shoot is the model's nose.
I have not tried the 100 f2 myself. It just seem to me like an out of place lens.
I mean, I have used the 100mm macro USM with great success for portrait at f2.8
I initially chose the 100mm macro for 1:1 macro, and did not consider portraiture specifically, I didn't seek buying a 100mm f2
There would of course be more blur in the bokeh with the faster lens wide open.
The 85 1.8 can make a great portrait lens, but is bokeh on the 135L is more fluid and less distracting.
The 135L give you the most compression, and marginally better colors and contrast as the L glass quality is known for.
I recommend viewing a sample thread..
https://photography-on-the.net …/showthread.php?t=1287825
https://photography-on-the.net …/showthread.php?t=1145005
And lastly I will share my own personal experience.
For me budget was a huge concern when buying my lesnes last year. I decided to try macro, bought a used 100mm macro (non USM)
I liked it a lot and decided to upgrade it, briefly considered the 100L but couldn't justify it. Sold the (non-USM) and bought the USM
Well 4 months (and several paychecks later) I decided to sell the USM and buy the 100L after all. No regrets on my decision. 
My point is this, while great photos come from all three lenses, You will get the best colors, contrast, and smoother bokeh from the 135L.
Since you listed it, you must be considering it. If that is the FL you need, then I recommend saving up the extra cost.
I am not saying you MUST get the L lens. I am simply saying if you spend that extra money you won't be disappointed with it.
In fact, you should buy all three used and try them out yourself. Then sell the one that interests you the least.
In another thread I was considering swapping my 100L for the 135L but could not give up it's macro abilities.
But then I would just need to re-buy a 100mm USM for macro. That would not suit my personal needs.