i both have the 85 1.8 and the 100L
and the 70-200 2.8 IS II
i gotta say, each lens is for a different purpose.
the 85 1.8 has very nice bokeh, but suffers from CA, the good news is that its cheap and lightweight
the bad news except the CA is the minimum distance.. you can't "crop" a face with it as you would with the 100L
many many times i find this issue irritating and thats my main difference with the 85 1.8 which is a great lens.
The 100L is made for macro, which means that you won't have that softness as you would with the 85 1.8
way too contrasted but excellent image quallity, and nice build. Plus the IS and of course you can shoot tight portraits with it without cropping in post afterwards.
The 70-200 2.8 does a bit of everything. The good news is that this lens is sharp and focuses blazing fast. It doesn't think. It acts.
The bad news except the cost is the weight.. not versatile. I use this one for weddings mostly where i need a tiny window to shoot through at 135-200mm @ 2.8 but not to take photos of children at home. hell no. It is scary and uncomfortable.
I'd probably use the 85 1.8 or the 50 1.4 which i also have and love for that
if i have space and time to play with i'd use the 85 1.8
if not, 70-200 2.8
I think i'm gonna sell the 100L, i'm too lazy to shoot macro anyway. Besides macro lenses are useless without proper lighting.