I've only just gotten back into film, and have tried every 35mm B&W film that's readily available. Delta 100 in DD-X is my hands down favorite, and it will be my 'go to' going forward. It also scans great, which is a bonus as I'm not going down the darkroom printing route.
I do have to admit, though, when I'm feeling a little nostalgic, I'll load some PanF+ or FP4+ in the IIIf and shoot with my 50/3.5 Elmar. This combo ends up being a little more creamy, little less sharp, and just has a great atmosphere. Of course, I'm still in the testing phase, those are just my initial observations.