Really the only choice is Kool Stop red or Kool Stop black. They are as far as I know the only pads available that fit the original holders. Yeah, you could use modern post type pads, but I prefer not to use dorky looking modern pad holders on vintage brakes. If for some reason I used modern pads, they'd be Kool Stop anyway.
AFA the Kool Stops I like the black because they work well and don't ever squeak. Reds are kind of cool if you live in a rainy area. The stopping power in the wet feels almost the same as it does in the dry.
The original pads worked well, but that was 30 years ago. They were very similar to the Kool Stop black. Any still around are too dried out to be usable.