The 85 1.5, 50 1.4, 100 f2.0 and 100 2.8 are all excellent portrait lenses for the value. The only comment I'd like to share is the Sigma 85 1.4 is a wonderful lens, though a bit pricey, and it has had focus issues. It is extremely fast to focus once it finds the spot you are registering. Excellent bokeh and contrast which is also true for Sigma's 50 1.4 for Canon.
In final summary, I'd probably go for the 85 1.8.
Best of luck.