Well, the 35mm will show more background behind the subject that the 50mm or the 85mm; the 85mm will be much more of a selective-angle type lens, whoich will tend to throw the backdrop more out of focus than the 50, and much more OOF than the 35mm. On a crop-frame Canon, I think you might actualkly like the 85mm for shooting things that are 50 to 100 feet away from you, or which are happening shall we say, on the oppoisite side of the street.
The Canon 85/1.8 EF is a solid lens. Had one, liked it, thougt it was a very good lens for the money. Not too big: far, far smaller than a zoom of comparable length.
For really tight, telephorto work, Canon's little 135mm f/2.8 Soft Focus lens is VERY sharp when set to SF OFF...and will focus pretty well on any camera. I had one for a number of eyars, and thought it was a good lens, and much smaller and more-discret than the 135/2 L.