Off the top of my head:- for our purposes (that is, the 8-bit micro scene) DS/DD (Double Sided, Double Density) at 48 TPI (Tracks Per Inch) seem to give best results.
Some folk reckon that it doesn't matter, and other formats (eg,
96 TPI) work OK as the formatter program will sort things out anyway.
However, I remain unconvinced, as the physical (magnetic, spacing etc.
) make-up of these various disks are different, all of which can contribute to (in my experience) unpredictable results.
Bear in mind also that we're talking here about disk drives themselves from an earlier age, some of which may have been heavily used, and not quite within original specs!
I made the dumb mistake a while back of wrecking a "new" (unused) disk with a hard-to-find program on it (specific to a particular sideways RAM board) by attempting to read it from an disk drive of, shall we say, unproven capabilities. Unfortunately the drive wrecked the disk. Playing about with this old kit requires a somewhat different approach, you know. Like proceeding at a measured, gentle pace, for instance.
Meanwhile, are you about to 'fess up, then, Neil ... to still having your BBC Micro to hand?