Kodachrome. I owe it my career in calendars. I couldn't have done it so conveniently without it.
Great skin colour, travelled very well and the latent image didn't fall into deep space if you couldn't get it to the Kodak place quickly.
But, there were times when it did go wrong, but as in the song, too few to mention.
FWIW I find that scanned, it makes better b/white conversions than does a straight digital capture on D200 or D700 cameras.
Best film I ever used in 135 format. Never had the chance to try it in 120 because I divested myself of that format just before Kodak introduced Kodachrome to it. Reports from some users say it wasn't as good.