It’s embarassing — I have way too many of these things for an adult of 36 years, but I’ve yet to find a suitable replacement.
My ideal milk crate replacement:
1) would interlock in both storage mode (stacking) and presentation mode (on its side),
2) would provide or accommodate an optional rail for filing,
3) would be free-standing,
3) would be sturdy yet classy (preferably not plastic),
4) would not put me in danger of going to jail or paying hefty fines.