I think it's obvious that what people mean is that "more unique" = "unique in more dimensions" or "the degree to which this differs from the norm is greater".

E.g. (2, 4, 7) (2, 4, 8) (2, 8, 4) (2, 4, 7) (1, 4, 8) (0, 9, 3) (987, 4, 7)

When asked what are the "most unique" sets in that list, you'd probably be acting deliberately obtuse if you chose anything but one of the last two.