Definitely the First Suggestion, mostly cause trying to downscale it all at once using the Nearest Neighbor will merge colors and some of the upscaled pixels would be lost during the one-time scaling.
Hence percentage is probably the best approach and doing it one downscale at a time. A.K.A. more than one Downscale node with percentage specification.
Admittedly I also like the Second Suggestion as well, but once again I prefer the First Suggestion to avoid loss of downscale/merged color pixels. :)