The 35mm is great, the 50mm is spectacular. I already have the Sigma 18-35 f1.8 so that pretty much covers all the medium-wide focal lengths for me (with a decent maximum aperture still).
I actually like the 50mm over any 85mm I've seen yet because the 50mm has a good minimum focus distance, which I use a lot. 50mm is still ideal for full body portraits, where 85mm is your minimum for head and shoulders portraits. Given that I've never taken a picture of just someone's head I don't actually see a need for 85mm, other than if you want "maximum bokeh".