I like the old 35/2 concave lens SSC II version I have. It is really, really sharp though it has a slight yellow cast. I hear the new ones are just as sharp but without the yellow cast but I've never tried one.
As I've mentioned before I much prefer my 28/2 to the old 28/2.8 that I had, both new FD mount.
I use a 100/2.8 (new FD) and while I yearned for a time for the 100/2 I never got it, I got an FL 85/1.8 instead. In fact I use the 100/2.8 more however, including a whole roll I recently shot with it using Delta 100 in my Canon TX. My copy isn't even in that great a condition but I still like the images it produces, go figure. Not sure why but the 85mm focal length has never appealed to me on 35mm cameras though I use 80mm on 6x6 and 90mm on 6x7 all the time as they're more normal lengths there.