What is your favourite aspect ratio? I don't want to limit the discussion to negative format, since it is possible to crop negatives. Also I believe some have several favourites depending on subject matter. Please make a list.
I calculate the aspect ratio the following way:
long side / short side = aspect ratio
eg. for 4x5" film: 5 / 4 = 1.25
Since I'm in Europe I find 4x5 LF format to be a little off with standard frames, so I'm actually going from 1.25 ratio to 1.33 by cropping my negs a bit. And actually I like the European format a lot :-)