The answer depends on what we value. Each slider sets how much one thing counts, and the list re-ranks.
How this is worked out
Future generations: a rule-of-thumb decay time from the object's lowest height (roughly a year at 400 km, 25–30 years at 600 km, 150 years at 750 km, many centuries above 900 km). It counts up to seven generations of 25 years, the horizon of the seven-generations principle. Real lifetimes vary several-fold with solar activity and each object's shape and mass.
Crowding: how many tracked objects share its height band, per unit of volume. More neighbours, more chances of a collision.
Size: a typical mass for its kind (named for the heaviest rocket-stage families, such as the ~9-tonne SL-16; otherwise ~1.5 t for a rocket body, ~1 t for a satellite, ~10 kg for a fragment), raised to the power 0.75, because that is how the number of fragments from a collision grows with mass in NASA's standard breakup model.
Shared skies: the share of the Earth's surface its orbit passes over, from its tilt.
The score multiplies the four, each raised to its slider's weight; a weight of zero leaves that value out. Satellites are left out by default because the public catalogue does not say which still work, though many, like Envisat, do not. These are open, rough estimates for thinking together, not an official risk rating.