Can I ask what you shoot exactly to be so sensitive to distortion (85L can be criticized on a lot of thing but its distortion is average at worst, generally unoticeable) andso averse to shooting wide open? just curious.
Anyway you seem set on the 100L (macro is a good reason)...as to the second one when I think portraits I think environmental portraits so 35 1.4 would be a nice idea but you don't mention it (and the 1.4 capability might be wasted).
I shoot a lot of vertical and horizontal lines in the backdrop, and it does show, and makes the whole image look cheap (like columns, doors, windows, striped floors and walls).
It's fine when there is only floor/wall line.
It is so easy to automatically correct lens distortions in post, you can even set the correction as an import preset so you do nothing, that distortion really isn't any kind of serious consideration. There is absolutely minimal IQ hit when doing simple lens corrections too.
How many times must I mention that it cannot be done in post without deforming the corners (you know those corners where models might be - yes, deformed shoes, hands, and elbows are not my cup of tea). Many presume that model is only to be put in the middle of the image, not touching the edges anywhere. Not the case with me.
Also, I often don't shoot directly, but at an angle, and then distortion really messes things up, especially when you have chess pattern, like I did last season.
So, I'll stick with the 100L macro and get another lens to join it later (presumably 200L 2.8 non-is or the 70-200).
Obviously it is better than 100mm USM macro.