Actually GEO is one of the worse orbits for this, because
1) unlike LEO, there's so little drag that both large particles and small fragments are essentially up there forever
2) all the satellites are concentrated in a line, not spread out in a 2D plane or (even better) a 3D volume (collisional probability scales as number density squared)
3) despite that, the moon perturbs any uncontrolled debris into a slightly inclined orbit that nevertheless crosses GEO with >500 m/s relative velocity
If you want to intentionally rendezvous with and deorbit satellite debris, GEO is certainly one of the orbits to prioritize.
